Constant limp mode.

[sharpshotta]

I'm having a limp mode problem with my gtr since I've had it. The ecu doesn't throw any codes when it happens, but i think I've narrowed it down to mafs. I swaped a pair a mafs in and car ran fine for 3 days, go to drive off to work and my car is in limp mode. Check the obvious thing first, codes, got a 55, reset the ecu anyways just in case, still in limp mode. Checked the forums to see other people who had limp mode problems, most seem to be maf related, so I picked up a pair of good mafs and switched the rear maf first, problem solved no limp mode. Went to pick up a maf to replace the bad one, put it in everything still good. Drive another 3 days, then my limp mode comes back. Checked the ecu, again, code 55. Call up my buddy and get his mafs again, switched the rear one, no change, switch the front one, car is no longer in limp mode. So i go buy another maf and again back to normal. Another 3 days and the car goes into limp mode again. So this time I decide to check the wiring, continuity test, voltage drop. Go to do my visual inspection of the wiring I find the plugs had been cut by the previous owner and new maf plugs soldered in about 6 inch's from the plug. Both are correctly wired. I also took the time to check, tps, cas, air leaks, ignitor swaped with a known working one, no change, still in limp mode. I even changed the ecu with a known working one and still nada.
I recently got my hands on a consult cable so I will be able to check real time data and see whats going on tomorrow when i go work on the car.
If anyone has any idea what my problem could be I'm pretty much out of them myself.
Mods on the car:
-M's intake with K&M filters, not oiled
-gt2860-7 turbo's bought brand new about 200km's ago.
-boost controller
-blitz bov's not recirc, I was running the car with stock setup at first and still had this limp mode problem.
-Stock fuel pump, wired directly to battery.
Everything else is stock.
Any input will be appreciated, I'm tired of throwing mafs at this thing and getting the same problem all the time.
I know it would be possible to fix my problem with nistune/any stand alone but that is not in the budget right now.
The only thing i would have access to would be an emanage blue, but no tuners around that want to work with it.

[sharpshotta]

Noone has any idea?

[bourquetc]

did u have the problem before u did the turbo swap?

[sharpshotta]

Ya i had this problem before switching the turbos

[Skym]

-M's intake with K&M filters, not oiled

If clamp onto (via intake hose clamp) adaptor that bolts to MAF type of air filters, the intake hose clamp can become loose and cause MAF to max out (hit boost / load cut or basically a fuel cut on ECU) and it seems like ECU in limp home mode when it's not. Common problem with clamp onto adaptor type of pod filters. Apexi podfilters that bolt on is the fix.

[sharpshotta]

I guess it could be, but that would mean my problem could manifest itself while driving, which it never has. it always starts doing the limp mode 2500 rpm cut after i would park it for the night and go to leave the next morning.

[Shane_Sawatzki]

i had an issue of random limp mode coming and going while driving...id be driving and the car ran fine, hit a bump then the car wouldnt rev over 2500 rpm.

I swapped mafs to what i thought was working mafs.

Long story short, my original mafs were bad... I swapped them with more bad ones that I thought were good, and i chased my tail for 6 months trying to figure everything out. I was ready to overlay new wires from the mafs to the ecu, but thought to myself "maybe ill replace the mafs ONE more time with guaranteed working Z32 mafs (was time for an upgrade anyway). Problem solved. Before the swap I was getting AFM codes, but not anymore.

So the bottom line for me was changing to Z32 mafs and re tuning Nistune for the Z32 mafs fixed my problem. Either I had bad mafs or one of the connectors on the mafs were toast. I cut and soldered Z32 maf plugs on and installed the z32 mafs and its been fine for 2 months.

So double and triple check anything you do, limp mode drove me nuts for over a year.

[sharpshotta]

The thing is my problem isn't happening while driving. I'd get home with no problem and the car would sit overnight and i go to leave for work the next day and it's in limp mode. And i always checked with a pair of mafs that come off a car with no codes or limp mode and the problem went away, but always comes back the same way.

[Shane_Sawatzki]

Check maf plugs for lose or corroded pins etc, peel back some of the wire loom and see if the wires are green/corroded badly. etc.

mine also would be fine one day and then the next morning be in limp mode.

like I said double and triple check every.

Also is it a stock ecu???? swap it with a known working ecu if its a stock ecu. I have seen on some cars if a car had alot of moisture in it at some point in its life, the ecu could have corrosion on it.

Buddy of mine had a turbo AWD plymouth laser that ran fine sometimes and then some times ran like crap, we swapped out EVERYTHING before the ECU , and it ended up being the ECU lol, wish we would have started there first since its easier than changing every component in the ignition system

[Skym]

If revlimit's at 2500rpm, like said above, wiring could be a problem (ECU doesn't see MAF or MAF's). When it plays up, sometimes tapping on MAF itself or wiring to MAF's makes it stop or start (if there's a loose connection). Pop lid on both MAFs (make sure you have high heat sealent for sealing around lid before doing this) and check for bad solder on plug side, circuit board. Then check wiring into ECU plug (make sure it hasn't come loose in plug or sometimes plug is not seated correctly in ECU and when tightened down the plug is warped) and like said above, check wiring into MAF plugs, as the wires can get pulled out of plugs if someone pulled on them when unplugging MAF's.

To know if it's MAF's, turn engine off when it happens, unplug both MAF's and start engine. If it stops, then found the cause. You'll need to clear MAF error code on ECU afterwards, so access to Nistune tuning software, consult cable, laptop is needed.

Also check position of diagnostic screw on side of ECU (make sure it's not in diagnostic mode, etc).

[sharpshotta]

If what stops? The engine or the rev limit? Wouldn't unplugging the mafs put me in limp mode so i'd still be stuck with a rev limit.

[Skym]

Oops, my bad. I was thinking of another thread / problem on here.

It will engage revlimiter at around 2500-3000rpm, use a preset load value on ECU when MAF's are disconnected.