My scan tool see only 4V at idle and can jump to 17V when i press throttle pedal.

When i turn the key but dont start engine scantool see 0 V
I have checked orange wires (pin B1 and C16) with voltmeter : 12.5V, battery 12.5V, voltmeter in the instrument cluster also see 12.V and 13.5-14.5 when engine running

Which pin ECM use to determine system voltage??

maybe pin A6?(look at image below)

also i have code 34 MAF low

 

Seems like floating ground problem.

Check volts from ECM-C14 to chassis ground, should be +5Volts
Check volts from ECM-D13 to chassis ground, should be +0Volts

Throttle position sensor(TPS) voltage C13/C12 @ idle position (throttle closed) must be less than +1.0volt, close to +0.55volt is target.

TPS volts (C12/C13) must vary with pedal position somewhere between +0.0 (zero isn't possible if adjusted properly and sensor is ok, 0.55 is target value) to +5.0 (+5.0 isn't possible if adjusted properly).

Perhaps there is an ECM chassis ground missing (Check D1&D6 = 0.0v to chassis) - confirm all ECM to chassis grounds, ECU +5V supply problem (bad ECM circuit), some miswiring of TPS, or faulty scanner.

Keep looking, good luck

 

.

 

thanks, i'll check it today


I tried to connect another ECM but scanner see low voltage too

I'm using AKM cable with WinALDL and notebook see right voltage and % (from ~0.7 to ~98)

 

Okay, Battey voltage is main supply, +5.0 volts is made from +12v by regulator circuit in ECM.

Ground reference is very important for measurement by voltmeter, also if +5V circuit is shorted to +12v circuit, you will obeserve more than +5v on TPS circuit.

Scanner is nice for dynamic measurement, but it seems this is a static problem and voltmeter is better.

Enjoy the experience!

 

Results:

C14 (tps gray wire with ignition "on") - 5.07 V
D13 (tps black wire) 0.03V

all ECM to chassis grounds confirmed

Still didn't check TPS voltage with voltmeter because i need to make jumper wires to do that

D6 (O2 ground) shorted to chassis ground, and D6 to chassis is 0 V

 

Seems like actual physical voltage is correct for 5V circuit, are there any drivability problems? If all physical voltages are reasonable does a real problem exist? Is this first time to try scan tool? Maybe scan tool configuration is incorrect for ECM type?

Anyway, while checking voltage, confirm all bat supply voltages for ECU as well. You have MAF low code, was this sensor working previously? (Of course confirm MAF voltage with meter as well, blue wire = 12V, brn/wht wire = 2.5V?) If not, and there was some recent surgery, maybe sensor is incorrect sensor for computer? Baby bird feather stuck in sensor (joking, ha!)?

Assuming there is an actual problem, there must be some history leading to the problem?

Are you having fun yet?

 

Thanks for helping me.

I just checked my friends car 2.8 89 camaro with automatic gearbox and WinALDL

shows same voltage. So i think it's not problem. Maybe WinALDL makes incorrect

readings of voltage. Also i've checked his MAF readings (~6-7 g\s at 1000rpm)

and compared to my (~3-4 g\s at 1000rpm). I think MAF needs to be replaced

Driverability is good until i get to the city traffic. I'm trying to avoid full

stops because car hard to take off. But when she moving she have great

driverability and throttle response.

I think its bad pressure plate because when it was disassembled i noticed that

1\3 of pressure plate fingers was bent, but after 15 minutes they back to normal

position. This pr. plate was bought on e-bay from this seller

http://myworld.ebay.com/thepartsladi and was described as AcDelco. It was writing

on the box "made in Korea" but on the parts inside "made in China".. I hate

chinese parts

This week i'll try to replace my flyweel and pressure plate with another one.

Used but original
sorry for bad english )

 

Okay, some of the older GM MAP sensors become flaky and intermittent with age. If you tap with screwdriver handle lightly on the sensor while engine is idling and idle changes, the sensor is bad.

Good clutch operation is essential for stop and start driving. Sorry about this problem, I don't know origin of Chinese parts but many probably aren't good quality. Maybe you can find quality parts from Summit Racing?

http://myworld.ebay.com/ebaymotors/summitracing_sales/

I use clean alcohol to remove oil and fingerprints from pressure plate during installation, used parts are okay if in good condition(not warped or scored).

I adore Russian accent, have many Russian friends here. Good luck!

 

By the way, to make a good chick magnet, some people connect their battery with reverse polarity. But unfortunately, this will damage/destroy alternator and maybe computer, etc. I recommend long shower, good aftershave and haircut instead.

 

Sorry, I meant to say MAF sensor, not MAP sensor.

 

thanks

About cluch if i will decide to buy new kit i think it will be centerforce http://www.centerforce.com/clutches....ption=clutches