91GTABird

Is no one calling out the BLMs of 108?

Is your blm staying at 108 non stop or is it fluctuating? Is it ever even reaching 128?

What prgram are you using to datalog? If your blm is staying at or around 108 then your ecm is adding fuel to the motor something major.

Justin 87 GTA

iTrader: (3)

huh? i don't understand. thanks

JP86SS

iTrader: (1)

At 108 Its pulling fuel out, not adding.

91GTABird

Oops. My bad. Thanks JP86ss.

What prgram are you using to datalog? If your blm is staying at or around 108 then your ecm is cutting fuel to the motor something major.

baerZ28

Just swap it for an LS1 ?????

91GTABird

i dont know your budget but yes, unplugging the MAF should make a difference. Have you tried a new one for a known good one? Im not a MAF person but i do know that unplugging a MAF on most cars not reliant on MAF & MAP will cause problems instantly. Did it not set a ses when you unplugged it?

What does your datalogging program show on your MAF for g/sec?

You basically have a new motor, sensors, and eeverything else so im curious as to whats wrong. Keep us updated and good luck.

rgarcia63

An 89' should have a negative back pressure EGR, applying vacuum only verifies that the diaphram moves as it should, but without back pressure (minimum 2000 rpm) exhaust gases will never flow. The ECM has no way of checking actual exhaust gas flow, it just cycles the EGR solenoid per the programming.
The EGR temperature switch will close when the engine gets to operating temp, then rev it up to 2000 rpm, and apply the vacuum with a hand pump and the engine should stumble, and die.

If you're not near inspection time, just remove and block the port until you solve the surging problem. It's only the EPA who cares how much nox you put out.

83TA-383

check exhaust pressure at o2 port!!!
could be clogged exhaust symtoms!
check the basics first.
also sounds like iac.

83TA-383

exhaust pressure should not get any higher than
3 psi up to 2000 rpm.

robsgta

Knock on your MAF with the handle of a screw driver at idle .

3.8TransAM

Ign module?

Flakey coil?

they both test good and can still be bad.

Check the grds on the pass cyl head?(at the rear)

Bad ignition swith causing low voltage situation(had this happen to me and never found it until it let the smoke out, what a pia lol)

Cracked reluctor or rusty distrib guts?

The absolute obvious lke a good cap and rotor?

later
Jeremy

DENN_SHAH

iTrader: (1)

along with most of the other replies, check all of your grounds, battery to both body & motor & motor to body, check them for voltage drops with the motor off & key off, then check them with
the motor running with everything electrical off & again with the motor running & everything electrical turned on, anything over 0.5 volts drop is too much. check the voltage in the data stream
to see what the ECM is seeing or what it thinks its seeing.
check for excessive A/C voltage from your alternator.

check for exhaust leaks before & just after the O2 sensor, do you still have the air injection on it, if so make sure the air diverter valve is working properly.

at 108 with a surge it sounds like you may be running lean, for what ever reason the ECM may think your rich when you really aren't & removing fuel. try adding some propane during the surge & see what happens. be sure to check all of your computer grounds with the motor running too.

rjt76

this may be silly but check your spark plugs. in a 1997 mustang gt i had the plugs were the expensive kind. They were actually not recomended for the car and they were comming apart on the electrode causing similar problems you are having... surging like the ac was coming on and off...

rjt76

sorry just reread and plugs were changed>>

robsgta

I wonder if his problem was fixed ??? any one know ?

jocool

If it was fixed it would be helpful to the group to know what was really wrong.