ecm gone bad?

[pwmin]

so, my car has been having this sputtering problem for a while just off idle till about 1500 RPM or so, so i tested the fuel pressure...good, the ignition system is good (new plugs, wires, coils ohm test good, icm bench tested good), etc. i tested the TPS voltage today and it was ready below spec in all areas.

 

so, i replaced it w/ a delco unit and the all hell broke loose. the car wont idle for shit and it bogs down when you give it too much gas. i did an idle relearn (actually about 3 or 4 total )and also replaced the iac and map for the hell of it. same thing. then, i put the old tps back in and same thing. i also got a code 22 (tps) and 34 (map). both are reading 0 volts now and both test charts led me to a bad ecm or wire, so its gotta be the ecm, right? there are a couple other codes, but nothing that serious (23, 35). i also did the tap test for loose solder joints on the prom and no change.

 

a little more history: i didnt do any tests, but it seemed like in the past when i would unhook the battery for a long time to do some repairs (im talking days to weeks), it would run fine for a while and then start acting up again, recently it has been the worst. the night my belt shredded, after i got a new one on, it was acting up after it had been fine up until that point. it also got better right away after i replaced the wires, but it was still acting up some, just not as bad.

 

so, do you think bad ecm? i cant think of anything else that would case both the MAP and the TPS to read 0 V.

[Pabz]

I would run temp wires to the TPS and MAP before blaming the ecm

[pwmin]

well, ken sold me an ecm for cheap, so i tried it out today. same thing. the problem has nothing to do w/ the IAC, MAP, or TPS (see later). after i found it it didnt fix the problem, i put the old ecm back in. i then pulled out the IAC and the TPS. i noticed a blown AIR fuse and the black connector on the harness that runs through the UIM (includes wiring for the TPS and all that) looked like it might be a little loose. i replaced the fuse (air delete so it wouldnt matter anyway) and unplugged the connector and plugged it back in. car ran great after that (besides problems of not having an iac and tps), so i put the IAC and TPS back in, started it up, still running good. so, i decided to take it for a spin...bad idea. after 1/2 mile of running perfect, she acted up on me again. if i would push the accelerator too rapidly or go over 12mph, it would cut out and surge. limped it back to the garage and couldnt figure anything else out. i did check the fuel pressure again and it was fine. wtf is going on? my dad keeps wanting to blame the cam timing and the ffp udp its gotta be something that feeds that harness w/ the injectors and sensors, but what fucking wire?

[Crazy K]

sorry to hear.

 

you have the 6 degree advance??? I need to learn more about it...... but If it is done the same as Johns.... his doesn't feel right.

[pwmin]

i was told 0/-13 was best for a 5-speed, so thats what i did. in short, i made 2 tools to hold down 1 cam on each bank at a time and did some math to find the arc distance on the crank pulley and marked it. it cant be that or it would act up all the time. its gotta be something else.

[Crazy K]

correct.

 

it has to be a sensor that is out of spec.

 

ecm temp sensor? i've had that act up.

[pwmin]

i dont see how it could be a sensor. when its acting up, it causes 0 V to the MAP, TPS, and MAT

[Crazy K]

i dont see how it could be a sensor. when its acting up, it causes 0 V to the MAP, TPS, and MAT

oh? must be a damaged wire??????

[pwmin]

i dont see how it could be a sensor. when its acting up, it causes 0 V to the MAP, TPS, and MAT

oh? must be a damaged wire??????

thats my temporary conclusion, but i cant figure out which wire it would be.

[Psych0matt]

I dunno, unless you are 100% sure the timing is right, it could do some funny things. I drove mine for 3 months last year not timed right, and in the first month i timed it about 3 times, all having different driveability issues. Not saying you're timing is off, but if one tooth is off somewhere you may not notice any problems till you get going a bit. just a thought. also, double check your plugs/wires? and the only other idea I might have is coils, maybe one is on its way out

[pwmin]

i checked out the ign system and all is good. im also getting good fuel pressure even when its bogging out. the original problem was intermittent, so i doubt timing being off would cause an intermittent problem. it wasnt so bad until i changed the tps, then everything went dead. i did something to get it to run decent for 5 minutes, but then it acted up again. im just going to try a CPS for the hell of it. i should be able to get some time on it later today and tomorrow, i just dont know where to look for a bad wire.

[Psych0matt]

That was my next guess, a CPS. all your plug wires are good?

[pwmin]

That was my next guess, a CPS. all your plug wires are good?

brand new magnecor KV85. when i replaced the old wires, the original problem went away for a while, but came back. the car actually was weak from 5500-7000 RPM before i replaced them, too, but that went away.

[pwmin]

not the cps. injectors tested good and theyre getting fuel.

[WC-Frogger]

WOW I have the same issue with mine runs fine then all the sudden hell come home!!! back fires and surges top speed 15 mph , I did notice though the speedo jumps and the low oil lite comes on when the issue appears.... I have done all the shit you have done, it really messes up on wet roads

 

I think a wire is the issue when it gets wet hard to find though by the time i get it back home runs fine , till rain or a puddle

[GP1138]

You're entirely sure the ICM and coilpacks are good?

[pwmin]

You're entirely sure the ICM and coilpacks are good?

yeah, had the icm bench-tested and ohm-tested the coil packs. i had to replace one a while ago.

 

the +5V wire to the TPS had a decent knick in the shielding. im hoping that was the problem. im going to cover it up and cover all the wiring on the harness tomorrow, put it back together, and hope it fixes it. my guess is it shorted out against the cam carrier and caused the ecm to go into a funk, or at least thats my hope. if not, its gotta be a wire that feeds the harness on the other side of the connector.

 

my booster hose is kinda messed up, so i think im going to drop it off in the morning and have a SS-braided one made. if theres enough interest after i get it, i may do some sort group-buy for them.

[Psych0matt]

hmm, I should have my ICM bench tested tomorrow just to see if that was actually what was blowing that fuse. what did you do to ohm test the coils? i mean what should i set my meter to, and what should I look for? (newb to using it, cheap 5$ one i got for free)