2.5 FMSC Odd Symptoms at High RPM [Archive] (2024)

E39S62

25th June 2016, 18:19

I'm seeing some odd behavior with my 2013 2.5 FMSC this summer. I'm looking for feedback on ideas where to troubleshoot next.

1) During WOT runs starting around 6k RPMs I get a vibration coming from the front of the car. Sort of whump whump whump whump sound. This ONLY happens when I really get on it.

I thought this might be a tire out of balance but the car ONLY does this under peak power, it doesn't happen at similar speeds at low RPMs. The problem is also independent of RPM if I gradually get on the throttle and run it up to redline no vibration or noise. I got the car up on jacks, removed the wheels and checked the suspension front and rear for any loose components or worn bushings and didn't see anything.

Driveshaft? Loose subframe bolts? Loose or shot engine mounts? Tire issue only at peak acceleration? Joe put in the 2.5 late last year and I've put 4000 miles on the 2.5 since.

2) While testing for the first issue and near red line the battery, TSC/DSC and CEL light all came on at the same time. Stopping and starting the car cleared the battery and TSC/DSC lights, the CEL code was P0112 "Intake Air Temperature Circuit Low Input".

I'm running the TMAP sensor in the SC housing and checked the wiring run and saw no issues. I'm wondering if this a heat related issue or if the electrical system simply glitched under load. The car heat soaks like crazy with the 2.5 and blower. I cleared the code and it has not returned.

Can anyone out there with a 2.5 FMSC report some IAT data under peak load in high summer temps?

Ted928

25th June 2016, 21:55

olgzr

26th June 2016, 09:49

Soraia

26th June 2016, 13:23

How are your MAFS wires and intake temp sensor wires connected?
You can check here on how I fixed up my connector related issues.

http://forum.miata.net/vb/showthread.php?p=8022780

E39S62

26th June 2016, 15:30

How are your MAFS wires and intake temp sensor wires connected?
You can check here on how I fixed up my connector related issues.

http://forum.miata.net/vb/showthread.php?p=8022780

MAF wires were soldered and heat shrunk by a EE friend of mine who spends his free time repairing old HiFi equipment as his skills with the soldering iron are top notch. The IAT wire utilizes a couple of the heat shrink splice connectors provided in the kit as when I swapped in the TMAP sensor rewiring was needed.

I pulled the wiring loom shield back and checked all the connections. I didn't see anything odd, also gave the wires a tug to see if any of the joins were loose.

I've only seen the IAT CEL once in conjunction with the high RPM noise.
I think olgzr may be on to something.

Soraia

26th June 2016, 15:35

E39S62

26th June 2016, 15:39

Just a guess, could your SC belt be slightly loose?

That could explain the noise and might explain the battery, TSC and CEL if the alternator cut out due to the belt being loose.

Any ideas on how to check tension? I visually inspected the belt and didn't see any obvious signs of wear. I pulled on the belt and there's no give but I'm not applying that much force manually. I'll give this a try though I'll need to get the intake and likely battery out of the way:
http://www.howacarworks.com/electrical-systems/checking-adjusting-and-refitting-drive-belts

Joe swapped on a Gates belt when he had the car last to address horrendous belt squeal. Gates Micro-V AT K061045 13/16" x 105" OC (20mm x 2666mm). I am running a 2.8" pulley on the blower.

The belt is back to squealing on startup but it shuts up within a couple minutes of driving. I think my attempts to adjust the power steering pump for alignment previously probably just made the squeal worse so I've let it be this time.

Ted928

26th June 2016, 17:22

That could explain the noise and might explain the battery, TSC and CEL if the alternator cut out due to the belt being loose.

Any ideas on how to check tension? I visually inspected the belt and didn't see any obvious signs of wear. I pulled on the belt and there's no give but I'm not applying that much force manually. I'll give this a try though I'll need to get the intake and likely battery out of the way:
http://www.howacarworks.com/electrical-systems/checking-adjusting-and-refitting-drive-belts

Joe swapped on a Gates belt when he had the car last to address horrendous belt squeal. Gates Micro-V AT K061045 13/16" x 105" OC (20mm x 2666mm). I am running a 2.8" pulley on the blower.

The belt is back to squealing on startup but it shuts up within a couple minutes of driving. I think my attempts to adjust the power steering pump for alignment previously probably just made the squeal worse so I've let it be this time.

I think that belt is too long for a 2.0L with a 2.8 pulley but it might be fine for a 2.5L. :dunno: I would ask Joe.

To check, you need to see if the tensioner is compressed adequately. Put a wrench on the tensioner and mark its orientation relative to vertical. Then torque the tensioner to unload the belt, slip the belt off a pulley, and let off the torque. Mark the wrench orientation relative to vertical. If the difference is small (less than 20 degrees or so), I would be concerned that the belt is too long. The next smaller length is 1040 which is 1/2" shorter.

E39S62

26th June 2016, 21:56

Here's the idler with the belt off. The ruler is marking the position of the wrench when the belt on, you see see the wrench. Looks like well more than 20 degrees to me.
http://i.imgur.com/ABzyi0e.jpg

I put the car back together and took it out for a spin. Nailed it through second gear and I get the same sound along with a flashing check engine light which left no codes. I assume that was a misfire. This car has had the problem previously at high rpms. Joe replaced the coil packs which had solved that issue.

Very frustrating.

dynotronics1

27th June 2016, 07:44

fastredrat

27th June 2016, 08:11

Been a few years since I've had the Cosworth SC, But the squealing noise reminds me of the high failure rate of the original 3 idler pulleys supplied in the kit. I knew a pulley was on the way out when it would squeal on start up. Not sure if they upgraded the idler pulley or not, but if Joe can not find anything in the log you provide him, I would strongly suggest checking the bearings on all 3 idler pulleys.

My write up on idler pulley failure:
http://forum.miata.net/vb/showthread.php?t=424704

dynotronics1

27th June 2016, 08:15

MXGeorge

27th June 2016, 21:35

Ted928

27th June 2016, 21:48

I'm seeing some odd behavior with my 2013 2.5 FMSC this summer. I'm looking for feedback on ideas where to troubleshoot next.

1) During WOT runs starting around 6k RPMs I get a vibration coming from the front of the car. Sort of whump whump whump whump sound. This ONLY happens when I really get on it.

I thought this might be a tire out of balance but the car ONLY does this under peak power, it doesn't happen at similar speeds at low RPMs. The problem is also independent of RPM if I gradually get on the throttle and run it up to redline no vibration or noise. I got the car up on jacks, removed the wheels and checked the suspension front and rear for any loose components or worn bushings and didn't see anything.

Driveshaft? Loose subframe bolts? Loose or shot engine mounts? Tire issue only at peak acceleration? Joe put in the 2.5 late last year and I've put 4000 miles on the 2.5 since.

2) While testing for the first issue and near red line the battery, TSC/DSC and CEL light all came on at the same time. Stopping and starting the car cleared the battery and TSC/DSC lights, the CEL code was P0112 "Intake Air Temperature Circuit Low Input".

I'm running the TMAP sensor in the SC housing and checked the wiring run and saw no issues. I'm wondering if this a heat related issue or if the electrical system simply glitched under load. The car heat soaks like crazy with the 2.5 and blower. I cleared the code and it has not returned.

Can anyone out there with a 2.5 FMSC report some IAT data under peak load in high summer temps?

Your belt length looks good. I went back to your original post and noted the this (in bold). Why do you think this? What IAT are you datalogs showing? With the ignition on, remove the reservoir cap and make sure you have a swirl.

E39S62

28th June 2016, 21:06

The good news:
I got under the car again and noticed that my GWR mid-pipe was pretty close to the frame brace. I removed the brace, loosened the slip joint, adjusted the pipe higher (pushed joint in further) and did some test runs sans brace. The noise is gone. I've reinstalled the brace and will do more runs to see if that was definitely the cause.

I feel a bit like a fool. Sound is very deceptive in a closed top miata apparently.

The bad news:
I'm now consistently seeing misfire (flashing CEL) on WOT runs at higher rpms.

The car had this issue right after the 2.5 swap. Joe tried to address it via tune (dwell) and had me gap the plugs down to .032 but it did not fix the problem. Joe had the car for awhile this spring and swapped the ignition coils with a set from a different motor. This seemed to fix the issue as until this week I had only seen the flashing CEL once since picking up the car in April. The car hasn't had a tune update so the only known delta here is elapsed time/mileage and the Texas summer heat.

MXGeorge - I believe Joe put autolites in the car, per the above I gapped them to .032 troubleshooting this issue. I don't know if Joe regapped them when he had the car last.

Ted928 - For IAT I'm see ambient (mid 30s C in ATX recently) on startup and it peaks at 105 - 108 C under boost once the car is warmed up. It might come down into the 80s C after cruising for bit. This spring I was seeing peak IAT in the 80s C. This is off the TMAP sensor in the SC housing.

It is beastly hot in the engine bay. I started another thread asking about radiator upgrades and hood vents got some good counsel. Sadly no one with direct experience with the new Goodwin triple pass spoke up. I defintely think the car needs a bigger radiator at this point, I may chuck the bigger SC intercooler and an oil cooler at it too while I'm at it. I've been eyeing the GWR 1.8 header as well. Perhaps a ceramic coating on that will help with under hood temps vs the current stainless max power header.

I'm reluctant to drop the coin on all of those upgrades while it's still misfiring though. I need to get the car sorted.

Ted928

28th June 2016, 22:04

E39S62

28th June 2016, 22:10

Those IAT are too high. Make sure you have the swirl.
IND did some good things to get his 2.5 FMSC cooler.
I have seen the misfire CEL issue discussed a few years ago. IIRC, the thought at the time was that the "unusual" time between crank pulses was causing the CEL.

Just checked, no swirl. Pump is running but there is no coolant. I swear I checked this a few weeks ago but I'm honestly not sure.

Going to refill and check for leaks. FM recommends 70/30 distilled water/coolant. Any thoughts on going with more coolant to raise the boiling temp as a safety measure?

Off to the store for some distilled water.

Ted928

28th June 2016, 22:26

Just checked, no swirl. Pump is running but there is no coolant. I swear I checked this a few weeks ago but I'm honestly not sure.

Going to refill and check for leaks. FM recommends 70/30 distilled water/coolant. Any thoughts on going with more coolant to raise the boiling temp as a safety measure?

Off to the store for some distilled water.

That is good that you found a problem.
My FMSC install manual says 50/50. If you do not need the best freezing protection (as you do not) then 70/30 (water/coolant) will give you better heat transfer performance.

E39S62

28th June 2016, 23:14

I went 70/30 and put in 2.25 quarts total counting a top off after a quick drive.

During the drive I pushed it a bit and saw the blinking misfire CEL. This time around the CEL stayed on, random misfire code.

But hey! The whump whump sound is gone! Stay positive right? :ohno:

fastredrat

29th June 2016, 06:58

I went 70/30 and put in 2.25 quarts total counting a top off after a quick drive.

During the drive I pushed it a bit and saw the blinking misfire CEL. This time around the CEL stayed on, random misfire code.

But hey! The whump whump sound is gone! Stay positive right? :ohno:

yeh, stay positive. One problem at a time.
Ok so you obviously have a leak in the intercooler piping. After you refilled, did you verify swirl? Burping the system has always been a pain in the butt.

Have you sent a log to Joe yet? Lots of causes for random misfire, in general air, fuel, timing, or spark issues.

Blackone

29th June 2016, 09:34

I'm seeing some odd behavior with my 2013 2.5 FMSC this summer. I'm looking for feedback on ideas where to troubleshoot next.

1) During WOT runs starting around 6k RPMs I get a vibration coming from the front of the car. Sort of whump whump whump whump sound. This ONLY happens when I really get on it.

I thought this might be a tire out of balance but the car ONLY does this under peak power, it doesn't happen at similar speeds at low RPMs. The problem is also independent of RPM if I gradually get on the throttle and run it up to redline no vibration or noise. I got the car up on jacks, removed the wheels and checked the suspension front and rear for any loose components or worn bushings and didn't see anything.

Driveshaft? Loose subframe bolts? Loose or shot engine mounts? Tire issue only at peak acceleration? Joe put in the 2.5 late last year and I've put 4000 miles on the 2.5 since.

2) While testing for the first issue and near red line the battery, TSC/DSC and CEL light all came on at the same time. Stopping and starting the car cleared the battery and TSC/DSC lights, the CEL code was P0112 "Intake Air Temperature Circuit Low Input".

I'm running the TMAP sensor in the SC housing and checked the wiring run and saw no issues. I'm wondering if this a heat related issue or if the electrical system simply glitched under load. The car heat soaks like crazy with the 2.5 and blower. I cleared the code and it has not returned.

Can anyone out there with a 2.5 FMSC report some IAT data under peak load in high summer temps?

I have seen the same similar symptoms when the CWSC is ruining out of injectors and just knocking hard.

I wrote some recommendations for those using smaller pulleys ruining 2.5l
Tuning Done Right CWSC Recommendations. (http://forum.miata.net/vb/showthread.php?t=611817)

The codes you got also merit some chasing if your FIDC is bellow 80% at max RPM

Soraia

29th June 2016, 10:10

E39S62

29th June 2016, 10:32

yeh, stay positive. One problem at a time.
Ok so you obviously have a leak in the intercooler piping. After you refilled, did you verify swirl? Burping the system has always been a pain in the butt.

Have you sent a log to Joe yet? Lots of causes for random misfire, in general air, fuel, timing, or spark issues.

Verified swirl. I unbolted the reservoir during fill to get it as high as possible to aide burping the system. Checked it again this morning.

Does anyone know the capacity of the system or what PSI it runs out? I have a HF cooling system pressure testing kit that is great at manifesting leaks.

I sent a log to Joe on Monday night, he's asked for an updated set of runs as there were issues with the file.

Soraia

29th June 2016, 11:13

E39S62

29th June 2016, 11:20

I have seen the same similar symptoms when the CWSC is ruining out of injectors and just knocking hard.

I wrote some recommendations for those using smaller pulleys ruining 2.5l
Tuning Done Right CWSC Recommendations. (http://forum.miata.net/vb/showthread.php?t=611817)

The codes you got also merit some chasing if your FIDC is bellow 80% at max RPM

Thanks Jay. I'm currently running the injectors that came with the kit and stock OEM fuel pump. I have the DW pump in a box and have considered picking up the KW800 injectors to run E85.

I've been working on a little Google script that formats my Ecutek logs for me and I'll add a FIDC column to the mix based on RPM and pulse width (http://www.stealth316.com/2-calc-idc.htm).

Joe would know better than I on fueling issues.

The working assumption is that this is a spark related issue with timing or coils in line with Ted's comments " IIRC, the thought at the time was that the "unusual" time between crank pulses was causing the CEL."

E39S62

29th June 2016, 11:59

If it leaks, you'll know. Nasty smell.
I think it runs constant speed, so you don't need to have the car running high load to test.

Thanks, I'll be keeping an eye on it. I did not see any leaks last night but I'll get the splash shield off and check under the car with the pump running later this week.

Having done the original SC install myself and the thermostats on several cars I'm familiar with the coolant smell. Nothing on rear diff oil though!

E39S62

2nd July 2016, 21:01

After a couple of days the reservoir is noticeably lower but I cannot find a leak in the system. I got the car up on jacks today and took the nose off in preparation for upgrading the radiator and ran the pump for a solid 10 minutes and looked over everything. I tried pulling and flexing the hoses too. Is it possible for these to leak inside the SC housing?

I sent log files off to Joe earlier this week and haven't heard back. The car will be out of commission for a week or two as I'm waiting on the parts and will be out of town travelling.

Ted928

2nd July 2016, 21:15

After a couple of days the reservoir is noticeably lower but I cannot find a leak in the system. I got the car up on jacks today and took the nose off in preparation for upgrading the radiator and ran the pump for a solid 10 minutes and looked over everything. I tried pulling and flexing the hoses too. Is it possible for these to leak inside the SC housing?

I sent log files off to Joe earlier this week and haven't heard back. The car will be out of commission for a week or two as I'm waiting on the parts and will be out of town travelling.

I have not heard on a charge cooler leaking but it certainly is possible. If you are sure that the level is dropping, I would pressure test the cooling system. I do not have a pressure tester but there have been many times I wish I did.

E39S62

2nd July 2016, 21:24

I have not heard on a charge cooler leaking but it certainly is possible. If you are sure that the level is dropping, I would pressure test the cooling system. I do not have a pressure tester but there have been many times I wish I did.

I'm sure it's dropping, I put in 1.5 cups of coolant over three days. I do have a pressure tester and will hook it up when I get the new radiator and intercooler installed.

E39S62

26th September 2016, 19:56

Just wanted to update this thread and say that the noise I was dealing with was apparently shot engine mounts or a loosely bolted passenger side GWR 2.5 drop bracket. I installed a pair of GWR's "competition" engine mounts today and the noise and vibration is gone.

The passenger side bracket bolts came out with zero effort, possible they were a little loose. I'll leave it to you guys to make comments on the state of the old mounts.

Here's a pic of the OEM engine mounts, passenger side is on the right:
http://i.imgur.com/BLtUhfGh.jpg

E39S62

17th January 2017, 01:57

Update on may various FMSC 2.5 issues.

The supercharger heat exchanger WAS leaking. I ended up pulling the heat exchanger out of the SC housing (possible in situ if you remove the SC intake, PITA) and found coolant inside. Though the exchanger held 20 psi with rigged up tester (see pic) Flyin Miata and Magnuson both agreed it was the only possible source of the leak as my throttle plate is not rigged into the engine coolant system. Presumably leaking at higher temps or vibration as my tester held pressure for hours.

$$$ later and I've replaced the exchanger. So far no sign of leaks. I do still have a high RPM misfire on multi gear runs. Joe, if you are out there, contact me. It's definitely not coolant causing it at this point and the problem has been persistent since 2.5 install over a year ago.... Eager to dispense with flashing check engine lights and put some actual miles on this car.

Kudos to Eric at Flyin Miata for his patience and guidance on this and dealing with Magnuson on my behalf.

E39S62

17th January 2017, 02:03

Pics!

Heat exchanger with my pressure testing rig:
https://uploads.tapatalk-cdn.com/20170117/0c990f7b3b2dbb5e00c0bb16d8913008.jpg

Supercharger housing heat exchanger cavity post a little cleaning:
https://uploads.tapatalk-cdn.com/20170117/4ece0ecef104bc836376d37f7a5db178.jpg

Rounded out hex key fastener, stripped even with care. Had to carefully drill it out with left hand bits. Sourced better fasteners from Fastenal. The other five bolts are regular 10 or 12mm, the Allen bolt is for clearance for the intake, tight fit.
https://uploads.tapatalk-cdn.com/20170117/26ac0e4b338f9353d403c07cc053132c.jpg

E39S62

16th March 2017, 02:25

8 months after initial post I'm still seeing misfires at high RPMs on multiple gear runs. If I keep it under 6500rpm the misfires are rare but still occur.

Joe has been incommunicado for months. I'd like to put in the upgraded DW fuel pump and injectors I've had collecting dust for more than a year and go E85 but need to figure out the tuning situation. I installed the flex fuel sensor and gauge months ago.

For the time being I need to put 800 miles are so on the engine as is and send off a follow-up sample to Blackstone Labs. Previous sample showed coolant contamination from what I assume was blow by from the SC heat exchanger leak. I plan on verifying things are kosher in the oil pan before adding another variable (E85) to the mix.

Car pulls very strongly in the cool weather out here (60F evenings) and is traction limited in the first two gears. Lots of smiles, it's good to enjoy the car after almost a year plus of mixed issues!

Soraia

16th March 2017, 16:13

Ted928

16th March 2017, 22:12

8 months after initial post I'm still seeing misfires at high RPMs on multiple gear runs. If I keep it under 6500rpm the misfires are rare but still occur.

Joe has been incommunicado for months. I'd like to put in the upgraded DW fuel pump and injectors I've had collecting dust for more than a year and go E85 but need to figure out the tuning situation. I installed the flex fuel sensor and gauge months ago.

For the time being I need to put 800 miles are so on the engine as is and send off a follow-up sample to Blackstone Labs. Previous sample showed coolant contamination from what I assume was blow by from the SC heat exchanger leak. I plan on verifying things are kosher in the oil pan before adding another variable (E85) to the mix.

Car pulls very strongly in the cool weather out here (60F evenings) and is traction limited in the first two gears. Lots of smiles, it's good to enjoy the car after almost a year plus of mixed issues!

Give NGK Iridium IX a try. I had some random misfire at high boost high RPM and those got rid of it.

I agree - first try plugs. Denso ITV24 is what I think Jay recommends.
Second is fuel pump. I suspect that the stock pump may not be enough for you.

E39S62

16th March 2017, 23:26

I ordered the NGK Iridiums earlier today, those will go in this weekend.

I've had the DW65c fuel pump sitting on the shelf for over a year. I can put that in but I'd want to get an updated tune. I reached out to Jay via his contact form to see if he wants to take on my car.

DrakeNC

18th March 2017, 11:29

Mike from Moto-East put out a PSA about the stock fuel pump units being potentially insufficient for High RPM boost runs despite improvements to injectors.

https://forum.miata.net/vb/showthread.php?t=630285

Your symptoms seem to mirror what he has seen multiple times so it is certainly plausible that you may have the same issue as well. Major lean out past 6300rpms due to insufficient fuel delivery.

I didn't see you make any mention about your data logs. It's crucial that you try to review them since it is an essential troubleshooting tool if you have the means to do so or have somebody interpret the logs for you. It's the only way to truly know for sure without having to easter egg parts(randomly replacing parts without troubleshooting).

E39S62

21st March 2017, 03:02

fastredrat

21st March 2017, 06:42

I'm talking with Jay (TDR) about taking over my tune. He mentioned upgrading both pump and injectors. I'll update here as things unfold.

You will not be disappointed with Jay and you will love the results.

Baba Ganoush

21st March 2017, 20:50

You will not be disappointed with Jay and you will love the results.

+ 100000000