Limp Mode.......need help & advise!

[326_godzilla]

I wanted to post here to get some helpful advise. Sorry for the long post, just thought i'd gather some thoughts and some ideas:

* Drove home one night and I noticed a weird sputtering sound and loss of power. This was right after i drove through stripped highway in preparation for paving. Because of my suspension (APEXI N1s) the car had loud rumble and vibration.

* The exhaust temp light started flashing and sometimes stayed on for about 30 seconds. At this time the car is in limp mode and i had to drive home.

* So i get home turned off the car and pulled the battery and discharge by pressing on the brakes. I turn the car on again after 20 minutes of the battery being pulled and started the car...still in limp mode.

* The next day I ran the ECU diagnostic codes and found the code to be 12 (MAF sensor circuit) Air Flow Meter. Took off the MAF sensor and gave it a clean (MAF sensor cleaner spray). Popped the MAF sensor back in and the car ran fine after a hard test drive. Parked the car, let the car heat soaked then tried starting again...again the car sputtered and onto the limp mode.

* Onto the next day, found the soldering fix in skyline australia and cracked open the MAF, found the solders are in fact weak where the pins connects, applied good amount of solders. Drove the car again and replicated what I did previously and seems the car is back to normal. (drove hard + park + heat soaked + re-start) Re-sealed the MAF sensor.

* The next night I went to a meet and we did a cruise there (i meant no hard driving, proper shifting, no hard pulls). Parked @ the underground meet and let the car sit for about 2 hrs. On the way home, started the car and I noticed the sputtering sound is back and behold the limp mode was back.

* Another day with the car, checked all the voltages of the MAF sensor and ran trouble shooting the service manual provides (all voltages checked out with the MAF). Ran ECU diagnostic check again, this time code 55 (All OK!) Had my friend come over and plugged in his working MAF and the same limp mode is happening again.

At this time I am looking into checking if there are any vacuum leaks etc. Now any ideas GTRC??? little help pls.

Thank You in advance!

[DarkCaporaL]

Does your exhaust temp still light up? Maybe your cat is stuffed?

[326_godzilla]

Not after i ran the code again and got the no fault code 55. How does one check for a stuffed cat?...sorry if its a stupid question.

[DarkCaporaL]

As far as I know the cat overheat light should only come on if either the cat is overheating (stuffed), or if the sensor is not grounded. A stuffed cat creates masive amounts of backpressure and makes the car feel like the parking brake is on. You would need to take the cat off and look at it.

I was just throwing it out there since you mentioned the light came on.

[Skym]

I agree^^^. I think when exhaust temps excede 800? degrees, the cat overheat light should light up.

Also cat overheat light can mean ECU is in diagnostic mode, not run mode (cat over heat light acts as a engine check light). It can happen if screw on side of ECU is not set to run mode (happened to my car). It would flash when hitting bumps in the road.

[326_godzilla]

Ok, i'll check the CAT and the sensor...also for boost leaks / vacuum leaks. Thanks for the replies and if anybody else has experienced this let me know.

[326_godzilla]

*** Update ***

- removed the CAT (well put to the side as the back bolts won't come off!) and drove it around the block
- still same issue...
- did more search on here and found this: http://forums.gtrcanada.com/general-...k-failing.html
- put the CAT back, removed the coil pack cover...
- tested all coils, normal sound for all when removed and re-installed
- the main coil pack connector (silver square module) seemed loose, re-installed and ziptied for tightness
- the car is NORMAL!.....

I left the cover off and drove it around hard last night! The car is driving really well...we'll see how it goes as I would be driving it this week to further re-create all the scenarios.

Thanks for all the input and post GTRC!....stay tuned.

[Skym]

Good to hear.

Interesting. ECU must have been picking up knock? Never known my car to do that with engine check light. I guess we learn new things everyday.

[Vulcain]

You run with Power FC??

[326_godzilla]

*** Update #2 ***

- so ran the car yesterday, worked fine after driving + park + turn off + drive + park + drove home
- while driving home i was stopped @ an intersection and all the sudden the choking, sputtering came back!
- drove 5 minutes till i got home, the entire time it was coming in and out of sputtering / loss of power
- just now started it cold, all good...then shut off car after warming up...the sputtering / loss of power is back AGAIN!

Any clues?

[cschepp]

Seriously man I would try the ignitor on this. Talk to a local buddy with a Gtr and I put my money on it that this will solve your problem. This is a quick easy fix and shouldn't cost much either. Please let me know how things go, I will be paying close attention to this

[326_godzilla]

Seriously man I would try the ignitor on this. Talk to a local buddy with a Gtr and I put my money on it that this will solve your problem. This is a quick easy fix and shouldn't cost much either. Please let me know how things go, I will be paying close attention to this

what other ways would I check the ignitor? I did a search and some have tried to check the ground on the ignitor...use a multi-meter and it checks out...ground not an issue.

maybe the unit itself?

[326_godzilla]

I will try someone elses ignitors lastly. Also from what I've noticed it seems the car is fine 'cold start'...runs normal...took it around the block with no issues. Then i turned off the car for a good hour, started again and it sputters / loss of power / no revs past 2000K RPM.

What is going on with my car?

[Daryl @ RightDrive]

Did you manage to find a fix for this? We have a customer with the same issue, very frustrating...

[Skym]

The rev limit points towards MAF problem, as ECU engages a revlimiter when there's no MAF present. Also stock ECU uses a default value for MAF's, so engine can be started, etc (stock ECU only feature). Unplug both MAF's and start engine. If sputtering problem disappears, have found the culprit (you'll need to clear MAF error code afterwards by resetting stock ECU via pulling battery terminals off or at least the negative terminal and pressing brake to remove any left over charge).

Sputtering can be a airleak behind MAF (2 airsources instead of 1), either intake hoseclamp has made a hole in rubber intake piping (under intake hoseclamp), cracks between ribs on rubber intake pipe, intake hose clamp not tight enough on MAF.

Other problems are loom problem on ECU plug or MAF plug side (sometimes loom plug is not seated correctly into ECU or is bent due to not being seated correctly and tightened down) and can be tested via multimeter at ECU plug for MAF'S to see if voltage reaches ECU from MAF's. Sometimes people pull on MAF loom instead of MAF plug and pulls wires out of MAF plug. This can happen with TPS plug, etc as well. With TPS, sometimes wiggling TPS plug gives it away as engine splutters and nearly stalls. Or check TPS via multimeter as sometimes it doesn't show up as a TPS error code on ECU.

With MAF it can be a bad solder problem inside square part on MAF (pop lid, resolder plug to board, reseal with high temp black sealant to keep water, dust, etc out).