CEL above 5k or so?

[m_dudey]

Hey guys,

got a s52 swap converted to obd1, 3.5 hfm, stock injectors, mated to a getrag 260 with stock flywheel, and a TRM chip for the above mods with limit of 7k for 91 octane fuel.

when I'm revving out a gear, the check engine light comes on around 5500 rpms or so. it just flashes on for the time that the RPMs are above 5500 then turns back off when the revs drop.

Normally, the CEL is off and the car idles and runs great. even when revving it up through the gears, the car feels great. No indication of a problem except for the flashing CEL.

I did the stomp test and got 1215, which is Air Mass/Volume Sensor

1215 - Indicates problem relating to Air / Mass Flow Meter - AFM or MAF depending on your e30 model. Causes could be cable wire damage, short circuit in the unit, or air / vacuum leak (check air intake hose - big L-shaped one)

Anyone else have a similar problem? Any guesses at what the problem is? or suggestions to fix it? I'm just hoping the engine isn't running too lean when it's in high rpms.


Matt from TRM, I'm hoping you'll respond to this thread...

[Adrian_Visser]

Well captain obvious has to ask have you tried swapping the HFM with another one?

[E30FTW]

You are using the 540i HFM right? Try clocking it differently and see if that alleviates the problem.

Also I don't know about TRM, but with Turners software for the same mods the CEL will flash at high RPM's with a 540i HFM... and go away the instant the revs drop. The software isn't intended for the 540i HFM, but the euro M3 one, and they are different.

If you put a DMM on the meter and go drive around I think you will find the meter to be maxing out.

[Dominic49]

the same light comes on with my TRM custom tune and a BRAND NEW 540i maf at 7krpm i use it as my shift light..

fyi if you have a filter mounted directly to the maf it will exacerbate the problem. also the light used to come on at 6k before i swapped for a new maf

[m_dudey]

I have not tried another MAF yet. I will once I get the opportunity to swap with someone else.

but in the meantime, clocking it to another position, I'll have to try that. And yes, I have the 540i MAF. maybe I'll try cleaning the MAF too.

my filter is mounted to about 6" of tubing before the MAF.

[matt]

If you put a DMM on the meter and go drive around I think you will find the meter to be maxing out.

No way. Nobody is maxing out a 540 MAF with an NA car. Also, the 540 and Euro MAF are the same except for the mounting configuration. Same sensor in a different tube.

Let me talk to my tuner and see what he thinks the deal is. Its a weird problem. The only time I've heard of this happening, it was a knock sensor code and the issue was related to the wiring harness. Generally a MAF code will trip and stay on permanently.

In the mean time, if the car is running right, i would not worry too much about it. I will get back to you as soon as I can.

[E30FTW]

The CEL flashing near redline with a 540i HFM is very common. On BFc there are numerous threads about it, and TMS said at one point that it is a 540i HFM issue, and using a true euro M3 meter would correct it. I'm using a Porsche 803 so eh...

Often times playing with the clocking or the length of tubing in front of the HFM can help or remove it all together, but not always. Either way no one has ever complained about it causing any issues, other than what is essentially a shift light :rofl

[matt]

The CEL flashing near redline with a 540i HFM is very common. On BFc there are numerous threads about it, and TMS said at one point that it is a 540i HFM issue, and using a true euro M3 meter would correct it. I'm using a Porsche 803 so eh...

Often times playing with the clocking or the length of tubing in front of the HFM can help or remove it all together, but not always. Either way no one has ever complained about it causing any issues, other than what is essentially a shift light :rofl

Well, I just got this same reply from the tuner. Apparently it can be an issue relating to turbulence from the intake or a dirty MAF. I guess I just hadn't heard of it before.

So I would try swapping MAFs with a friend. If that fixes it, maybe try cleaning your stock one. If that doesn't fix it, post pics of your intake and we'll see if we suggest some changes to try.

Do you have the flow straightening screens on the MAF?

[m_dudey]

Yes, I do have the straightening screens on the MAF. Will post pics of my setup soon.

[daniel]

I thought the check engine light was the shift light? :nice:

[RJ's325ITS]

Hello guys, It's not the tune I won 2 championships with it.....

I thought I might share some light on this subject/issue, I want to make my story short and to the point.

I had this 1215 code after swapping my original M50 for a M52 in my GTS-2 race car, the old M50 had 180psi compression across all cylinders but #4, #4 came in at 160psi, so needles to say after 10 years of track abuse and winning 2 southeast championships it was time to retire it.

Nothing change when I did the swap, the TRM tune was dialed in for the ODB2 pink injectors and that was it. At the dyno we saw no issues but soon during the first race of this year I found out the check engine light flashing at high RMP, and mostly on 5th gear.

BTW, I even put the car on the dyno at ran it thru every gear to try to replicate the issue, but never did it on the dyno……..

As I try numerous things the issue change its behavior, at some point it was only in the top of 4th and 5th gear but right before I fix it, it got really bad and the CEL will flash at any gear but high on the RPM.

Here is a list of things that I tried, in the order I replace them (nothing on this list fixed it):

1. cleaning the Air mass meter (HFM)
2. Tested the intake system for vacuum leaks.
3. Changing the air filter to multiple brands (OE intake box)
4. Installing a CIA w/a ITG filter and a K&N
5. Changing the OBD2 intake manifold to the OBD1 M50 manifold
6. Replacing the Crank sensor
7. replacing the engine temp sensor
8. replacing all coils
9. swapping the O2 sensor
10. Isolating the intake box from chassis harmonics.
11. TRM Tuning burn me a new chip
12. Different gasoline.
13. Injectors got serviced
14. replacing the air mass meter
15. Swapped DME’s
16. replacing the ICV

So Michael at TRM and I tried different things, and scratched our heads on this, and probably replaced sensors that were the originals, so some of them was just a must, and since the car is on solid mounts everything gets extra rattled.

So one day I started looking at my throttle data from one if my races at CMP, and I’ve notice one unusual read at idle, so base on that I took my bag of spare TPS sensors and ICV’s out and started to swap them, I found a newer ICV cleaned it and install it, then I found out that one of my spare TPS sensors actually got the DME to throw the TPS code rather than the 1215 AMM code… I smiled and started to log voltages, that one sensor was reading at idle below 1v somewhere around 0.4v.. so pull another one out the bag and that read 1.1v at idle, went for a test drive and voila the issue was gone….

I was able to do my last race at CMP with no issues, I hope this helps the community and if you want to say thank you, please support my sponsor since without them finding this issue would’ve taking much longer and probably would’ve have to race at the NASA Nationals with it…

https://WWW.TRMtuning.com

https://WWW.jacksonmotorsportsgroup.com

Rafa,

[328ijunkie]

Tps is supposed to read ~.5v when closed.. And ~4.5v when WOT

[RJ's325ITS]

Tps is supposed to read ~.5v when closed.. And ~4.5v when WOT

I will check the voltages on the car tomorrow b/c I fixed this a little over a month ago, and I might've had my voltages backwards ... I just have not had the time to post my results since I've been on tour with BMW doing the UDE ;D.

[ForcedFirebird]

Tps is supposed to read ~.5v when closed.. And ~4.5v when WOT

Confirmed. I use aftermarket adjustable TPS's on the ITB's and have to adjust them to read .5-4.5 give or take half volt when setting up the kits. If the ECU sees 0 or over 4.7-ish things get weird.