Bad Maf??

[Cheesehead]

About a month ago I converted my 85GN to 87 ECM and switched the MAF to a new Tomco unit from Postons. Haven't been able to get the car to idle and accelerate without surging since the switch.

Turbolink shows that the O2 delta crosscounts drop to 0 at idle, and the 02 voltage drops to 70 mv and then it stalls and/or sets a Code 44. I thought the the problem was the 02 sensor or the pigtail connector. I have tried two new 02 sensors and replaced the connector. No improvement.

This morning, I tried disconnecting the MAF. This instantly took care of the idle problem and the 02 delta crosscount problem also went away.

This is probably a dumb question--Does this definately mean that the new MAF is bad?
If so, is it worth trying another Tomco MAF? If not, what else could my problem be?

 

[SLOW_85]

Well with T-Link you should be able to see some MAF readings.
I would try the 85 MAF, to see if it makes a difference. Possible
you got a bad MAF. I have purchased 2 Tomco's and both work
fine. Sounds like it's not measuring the air flow.

 

[Cheesehead]

Thanks for the reply Slow_85.

Will the '85 MAF work well enough with the 87 ECM for a meaningful test, or do I also need to switch the ECM back to the 85 unit (hate to switch too much at once when I'm trying to isolate a problem)?

 

[SLOW_85]

It should run better with a good 85 MAF, if that's the prob. It will
throw a code.
For better driveability, yeah go back 85 maf,85 ecm.
Only alternative to a 87 maf is the Translator,LT1 maf setup.

 

[Men in Black]

When I did the changeover to my 85, I got the maf from Conley's Performance, and haven't had any problems.

 

[Cheesehead]

I tried the 85 MAF this morning. It ran better with the mismatched 85 MAF and 87 ECM than it has for the last month with the bad Tomco (87) ECM (no SES light, but it did set a malfunction code in TLINK). Finally, I am getting some meaningful #'s out of TLINK.

Next step is to check with Postons on returning/exchanging the defective MAF.

Thanks for your help. Maybe I'm get this thing running right just in time to put it away for winter storage.

 

[HOTSIX]

Guys...will a car start with a bad MAF or with it unplugged ?

 

[dave84gn]

will a car start with a bad MAF or with it unplugged ?

I'm pretty sure it will. I've heard people say their car idled better with it unplugged (bad maf I guess). I've never tried it myself.

good luck w/ur car man, I want you to get that thing going

Dave

 

[Cheesehead]

Mine both started and idled better with the MAF unplugged. It would also start with the bad unit connected. Don't know if there are circumstances where a bad unit would keep the car from starting.

Talked to Postons this morning about exchanging the defective Tomco unit--no problem, they said that they would ship me a replacement out today. Seem like nice people to deal with.

 

[SLOW_85]

Originally posted by Cheesehead

Talked to Postons this morning about exchanging the defective Tomco unit--no problem, they said that they would ship me a replacement out today. Seem like nice people to deal with.

Good people. I've been buying from them since, early 97.
Always excellent service, with no probs.