L98 Troubleshooting Question
Thread Starter
Cruising
Joined: Jun 2001
Posts: 12
Likes: 0
From: Mesa AZ
L98 Troubleshooting Question
Hey gang - I started up my 89 L98 this morning and it did something interesting. It started oscillating between 700-800 and 1200-1500 rpm. Then after about 20 seconds of that it just quit. And it would restart but not stay idling. The engine is bone stock, and very recently tuned.
Anyone have ideas as to where I need to start looking?
Thanks in advance for the help.
-Chris
Anyone have ideas as to where I need to start looking?
Thanks in advance for the help.
-Chris
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: L98 Troubleshooting Question (PagesterL98)
First off pull any stored codes; a scan tool would be very helpful here, to look at what the sensors are saying.
I would first clean the IAC motor and bore; it may need to be replaced.
If you can lay hands on another MAF, swap it in; when mine died it exhibited similar behavior and no codes. Run the engine with the intake disconnected from the MAF, have someone shut off the engine as you look into the MAF to see if the wires glow red hot for 2sec after shut off. MAF problems could come from the burn-off relay and/or the power relay.
I would first clean the IAC motor and bore; it may need to be replaced.
If you can lay hands on another MAF, swap it in; when mine died it exhibited similar behavior and no codes. Run the engine with the intake disconnected from the MAF, have someone shut off the engine as you look into the MAF to see if the wires glow red hot for 2sec after shut off. MAF problems could come from the burn-off relay and/or the power relay.
Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
Re: L98 Troubleshooting Question (PagesterL98)
What exactly was done in the tune? A visual inspection reveal anything? Maybe a disconnected vac hose? Hear anything unusual? Sucking sound? There are a few vac lines that become very brittle and break.
Thread Starter
Cruising
Joined: Jun 2001
Posts: 12
Likes: 0
From: Mesa AZ
Re: L98 Troubleshooting Question (89 Paul in Cal)
spark plugs, throttle body clean, injector clean, radiator flush, and oil change
just the basics
didnt get a chance to take a look last night, but the vac line idea sounds good also
thanks for the feedback :thumbs:
just the basics
didnt get a chance to take a look last night, but the vac line idea sounds good also
thanks for the feedback :thumbs:
Pro
Joined: Aug 2002
Posts: 698
Likes: 0
From: Richmond VA
Re: L98 Troubleshooting Question (PagesterL98)
I chased an intermittent idling/cut-off problem for MONTHS....did a complete tuneup...all new plugs, wires, distributor, etc......I tried everything.....I finally broke down and took it to the dealer. It wound up being the ECM. They installed a new one and I have had zero problems ever since.
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Re: L98 Troubleshooting Question (PagesterL98)
Mine did the same thing last year, just out of the blue. It turned out to be the IAC. Good luck! :cheers:
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Instructor
Joined: Apr 2000
Posts: 171
Likes: 0
From: waukesha, wi usa
Re: L98 Troubleshooting Question (PagesterL98)
Mine did the same very intermittently for several years. I would take it to a dealer and they couldnt find anything. I took a shot eventually at a new MAF Bosch unit from TPIS for about $250. Has worked fine ever since that was 2-3 years ago.
Instructor
Joined: Apr 2002
Posts: 159
Likes: 0
From: Delanson NY
Re: L98 Troubleshooting Question (PagesterL98)
I too have to agree and go with a faulty MAF sensor. When my went bad car would not idle at all, had to drive with 1 foot on the gas and the other on the brake. Replaced the sensor and all was good.
Good Luck
FRED
Good Luck
FRED
Instructor
Joined: Apr 2003
Posts: 112
Likes: 0
From: Front Royal VA
Re: L98 Troubleshooting Question (MyZ51)
My money's on the MAF
One would think that for the vacuum to cause that problem, you would hear the leak. Try pulling the codes. If that comes up empty, spend the $15-$25 on a new power and burn off relay before you go spending 10 times that on a new MAF.
Let us know what happens.
Thread Starter
Cruising
Joined: Jun 2001
Posts: 12
Likes: 0
From: Mesa AZ
Re: L98 Troubleshooting Question (DelcoVette)
Thanks for all the info - I checked all of the vac lines and they all seem fine. Then I was doing the test that 65Z01 mentioned and after I disconnected the intake from the MAF, I started it and it idled perfectly. I reconnected the intake and its still idling perfect. So, I guess that leaves me in intermittent idling problem land, which all of the feedback points toward replacing the MAF.
Thanks again for the help, this is absolutely the best Vette resource out there.
:cheers:
Thanks again for the help, this is absolutely the best Vette resource out there.
:cheers:
