97 D1 no acceleration with maf connected.

boxster

Well-known member
Jun 1, 2009
443
88
Fallbrook Ca.
D1’s been down for 2 weeks, between myself and the mechanic shop no resolve. Tried 3 different mafs 1 new and 2 known good mafs from running D1’s. The codes point to the maf but obviously not it. New fuel pump, pressure correct, etc. Unplugged maf goes to pre set values and runs right. From what I read maf signals ECU to fuel. I’m going to try a known good ECU and see if that fixes it. Read several posts with similar problem and a lot of detailed tests and parts replaced but no real solutions. Any ideas appreciated.
 

WaltNYC

Well-known member
Mar 3, 2010
707
135
NYC
Do you have a real time OBD reading capability (dongle / app)? If so, what does is say for vehicle speed? I'm thinking VSS (simply because you've covered quite a lot already) and the vehicle speed from the ECU would be wildly off with a bad VSS. Another approach would be to simply unplug the VSS in order to rule it out. This is merely a guess (low conviction), but the diagnostic is free so why not give it a shot.
 

boxster

Well-known member
Jun 1, 2009
443
88
Fallbrook Ca.
I thought VSS is for anti lock, lamp which appears on dash? I replaced once before chasing this same no power problem. Thanks
 

boxster

Well-known member
Jun 1, 2009
443
88
Fallbrook Ca.
My local mechanic shop has real time scanner. Didn’t mention anything about speed sensor. I’ll let them know. Thanks
 

p m

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Apr 19, 2004
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Greg,

OBD-2 capability is a great virtue. Trouble codes in most cases are hints rather than indications - but real time monitoring can tell you almost everything you need to know.
If you can't do it and your mechanic can't do it, find yourself a different shop.
 

boxster

Well-known member
Jun 1, 2009
443
88
Fallbrook Ca.
Told tech check VSS see what happens, could be the problem. Disconnect see if there’s change. I replaced it some time ago with no change. Was maf at the time being the problem. Will see what happens?
 

boxster

Well-known member
Jun 1, 2009
443
88
Fallbrook Ca.
ECU removed and opened up smelled burned, replaced with known good unit immediately normal running truck, as to the Maf wouldn’t run plugged in that was replaced as well along with a noisy alternator. Problem solved.
 
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boxster

Well-known member
Jun 1, 2009
443
88
Fallbrook Ca.
Greg,

OBD-2 capability is a great virtue. Trouble codes in most cases are hints rather than indications - but real time monitoring can tell you almost everything you need to know.
If you can't do it and your mechanic can't do it, find yourself a different shop.
ECU failed, installed known good one as well as maf and alternator started right up all power restored. Opened ECU smelled burned was the root cause. All is well. 😎