3k rpm limit, what now

mako18

New Member
Mar 15, 2008
64
0
0
FL
OK I have been trying to diagnose a issue with my brothers car. 91 targa turbo 7mgte forged rotating assembly .040, stock good working ct26 no play, 3 dp and exhaust.... Hes got about 10k on it and was running like a champ. until.....

Here are the symptoms and what I have tried based on searching the board, trouble codes and my personal knowledge.

The car starts up fine most of the time with real nice healthy start up no hesitation or anything. Then sometimes it acts as if the solenoid isn't even trying to engage not even a "click". Now you put a set of cables on it and boom starts up even though the battery has a full charge and the alternator is in proper working order verified via bench test. You can also push start it no problem every time. I checked the grounds, alternator, batt, the starter is only about 2yrs old and is a oem starter from Toyota dealership, cps wires appear to be good and the clip is nice and tight and clean.

The second and most important problem is the car cannot move at all until its been idling for 10min and is completely warm if you try to move it before its warm even moving the throttle a 1/4 of and inch with no load at all it will bog and try to stall if you let up on the throttle the idle will return and be rock solid as if there are no issues with the car at all!!! The other thing is the redline the car will not for any reason go above 3,000 rpm, in fact at about 2800 rpm it starts to cut or break ignition it falls to idle sometimes stalls other times catches itself and idles rock solid yet again...

First set of codes before I touched the car were: 42 speed sensor, 24 AIT sensor, 31 AFM, 43 starter signal. (the speedo is out too)

Now after checking the above mentioned items and for additional boost/vac leaks I reset the ecu by pulling the efi fuse for 30sec and I got another shot at attempting to drive it down the street. On that attempt it set code 31 which is AFM, AFM circuit , ecu according to trsm. So I swapped it for a lexus afm I had laying around same code so I am guessing the circuit is shorted somewhere? Could that really be whats causing all of this? Note there is no change in anyway with the afm plugged/unplugged which would support the shorted circuit. Yes of course the thing pops out the exhaust and has blueish smoke from and poor combustion obviously....

Fuel pressure is great. I just installed new plugs and wires (and yes 163425) also for shits I swapped coil packs.Tomorrow I will check timing along with the afm circuit, quadruple check the tps calibration and of course the cps. Engine is grounded at the motor mounts, block, head and of course battery.

I am a bit baffled this thing was running great then started this out of no where. After my list of stuff for tomorrow I will get a video if it will help stir up some ideas on what I am overlooking!?!?!? I am already thinking ecu but we will see!!
 

kingrichard

New Member
Aug 5, 2008
63
0
0
philly
did you say you swapped out the maf and its acting the same...i had a similar problem and thats what it was...maf or wiring to the maf..thats where i would start..
 

89supracrazy

New Member
Oct 31, 2009
317
0
0
wise
The afm will do what you said about the reving and back to idle. What you can do is go get you some spray air in a can, the one like you use to clean your computer out and spray the two little ports going into the afm. Make sure you do not turn the can upside down because liquid will come out and maybe destroy it. You do not won't to clean it with anything else because it will damage it for good.
 

89supracrazy

New Member
Oct 31, 2009
317
0
0
wise
kingrichard;1573352 said:
i would just get the maf cleaner at any autostore...

No. The afm is different from a mass air flow sensor. It is not a maf sensor it is a air flow meter. It has a mirror inside of it. Do not clean it with anything else other than air.
 

mako18

New Member
Mar 15, 2008
64
0
0
FL
OK I will try that its does look a bit dirty. I didn't have time today to mess with the car. Thanks for the suggestions I will report back!!
 

89supracrazy

New Member
Oct 31, 2009
317
0
0
wise
jetjock;1573738 said:
Actually that's one of the few things that won't hurt it, at least from a cleaning standpoint. It should still be avoided because of the cold though.



Yeah. I would not take any chances.
 

mako18

New Member
Mar 15, 2008
64
0
0
FL
I cleaned both afm's (the stock one and the lexus) seems there maybe some electrical gremlins nothing changed. I did notice the ecu gets pretty hot to the point where I cannot hold my finger on it for to long. This can't be normal?

Edit fixed the 3k redline!!! 3 out of 5 afm wires were snapped/loose in the harness under the loom. Looks like the afm plug was switched before and who ever did it used butt connectors instead of doing it the right way and soldiering it. I need a complete new 91 harness this thing is just crap all over!!!
 
Last edited:

mako18

New Member
Mar 15, 2008
64
0
0
FL
New issue I am getting a code 43 ..starter signal.... "no STA signal until engine is above 800 rpm with vehicle not moving". Now this is originally a auto car and I did the 5 speed swap about a year ago, never had any issues at all. I double checked the wiring and nothing is loose/shorted. I never pulled codes after the swap is this normal for a car with a auto ecu?

One other issue is the car will only hold an idle for a few minutes. Often it stalls when coming to a stop, after the tach surges and fails to find the idle it will die that is unless you nurse the gas pedal and help it find the idle. I am thinking TPS maybe? I have calibrated it several times I can check it again though!!!! Any other ideas? The car has a light weight flywheel maybe it won't compensate for the quick drop in rpm?