falling angel

1991 manual, s13 red top

My car was running very good after I had corrected a bunch of problems and replaced sensors. Drove in the rain the other day. Today the car completely cuts out at part, 25%, throttle. Just a tad of throttle is fine, harder acceleration is fine. It feels like a fuel or ignition cut.

Ive done:
-TPS
-Rewired ecu, found chaffed main power line
-temp sensor (for ecu)
-O2 sensor
-plugs
-maf working correctly, no hitches

Car runs strong otherwise. Though I will say that it has issues dropping idle to correct range. Sometimes it would drop, sometimes it wouldn't. It hasn't had this issue the last few times I've driven it though.

Car also gets up to temp really quick.. like within a mile down the road quick. Coolant definitely makes it through the radiator and the car is not overheating. Cooling fan works fine and the car has always done this. Doesn't lose coolant nor is there any smoke at all from the exhaust.

I don't have a timing light, nor was I able to locate loop at back of valve cover for ignition timing, may be suspect, but was running just fine otherwise.

Has a walbro fuel pump, stock pressure regulator though. I need to fix that soon. Aftermarket boost controler.


So far as I can figure, maaaybe something got into the maf from when it was raining, open filter where airbox would have been. But what I'm really suspecting is either the CAS or the ECU itself. The case of the ecu has some obvious signs of being exposed to moisture. I cracked it open and the circuit board itself didn't show any issues. The ECU also had a knock sensor code after I first had it plugged in... might hit the nail on the head there... I have about $500 on me right now that I would much rather spend on getting the suspension finished.

**Shortened story** - Would a faulty ECU tend to make the engine cut out at part throttle? Would the CAS do it?

I'm a mechanic so nothings too big an issue to understand, just not used to this kinda problem. Have consult port also set up, I'll try and see if that comes up with anything.

fliprayzin240sx

I'd double check your timing...get a timing gun, hook it up to the #1 cylinder for reference and you should be able to shoot it.

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KiLLeR2001

I'm assuming you checked the TPS voltages at full close and full open and everything in between (to check for any irregularities).

If you had some messed up ECU wires I would thoroughly check them all.

As for temperature reaching operating temp quick, you could test the resistance on the temperature switch for the gauge. I believe my brand new one out of box was reading 0.33 kOhms (room temp water).

Pretty much just double and triple check all the basics, sounds like something minor.

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falling angel

I've been through all the wires for the ecu, wasn't fun. I've also checked the TPS once I installed it. Was perfect then, but I'll have to double check. Suppose I'll go for timing next to rule that out.

AsleepAltima

when you check the tps, make sure it goes smoothly thru the voltage range - from .45 all the way 4+ volts with no dead or OL spots. actuate the throttle smoothly by hand with your multimeter connected to the right pins.

falling angel

Balls! TPS i just put in this spring is bad. Exact votage pattern that would be causing issues. Too bad it has to be modified to fit my automatic throttle body (don't think it had a warrenty anyways)

side note, the iac valve usually sits at 45% when it's idling high. Usually about 20% or so when the idle drops to where it is supposed to be. timing is about 24-26deg per the ecu at idle. Base idle mode drops to about 750rpm, or towards the low side of the in range zone (think this means timing is just a tad retard)