90 Power Loss (Help Please)
Thread Starter
"Rodstoration &am p;quot; In Progres
Joined: Jun 2004
Posts: 1,397
Likes: 1
From: Frisco TX
90 Power Loss (Help Please)
Need to ask for some help.
Am from the C3 forum and over at my Brothers trying to help him track down a problem with his 90. His vette has been running well until it began to get sluggish. He took it to the shop and they are saying that cylinders 3 and 7 are not firing properly. Mechanic noted that the spark is fine, fuel pressure is good, no codes and he can hear the injectors working. But told my Brother to note that when he unhooks the injector wire...the idle doesn't change...so there is a problem with the injector.
This doesn't make sense...especially to me who is use to carbs.
Seriously... could really use some advice on what we can look at to try to narrow this down and fix. Day is almost over here in Milwaukee and we were going to take his 90 to Bloomington tomorrow for the weekend.
Thanks in advance... Ed
Am from the C3 forum and over at my Brothers trying to help him track down a problem with his 90. His vette has been running well until it began to get sluggish. He took it to the shop and they are saying that cylinders 3 and 7 are not firing properly. Mechanic noted that the spark is fine, fuel pressure is good, no codes and he can hear the injectors working. But told my Brother to note that when he unhooks the injector wire...the idle doesn't change...so there is a problem with the injector.
This doesn't make sense...especially to me who is use to carbs.
Seriously... could really use some advice on what we can look at to try to narrow this down and fix. Day is almost over here in Milwaukee and we were going to take his 90 to Bloomington tomorrow for the weekend.
Thanks in advance... Ed
Drifting
Joined: Jun 2005
Posts: 1,426
Likes: 1
From: brookville pa.
90
could be any number of things from clogged cat to bad inj. as you said if you have a voltmeter you can ohm the injs. and they should read 15/17 ohms each more like 16/17 but if you have any that way off that the prob. maybe just a dirty fuel filter
Heel & Toe
Joined: Feb 2005
Posts: 20
Likes: 0
sluggish
I had a similar problem just a month ago and barely made it home. My 90 was overheating, choking and more. The '90 cat was falling apart inside and the engine could not exhale. One easy check is to jack it up and wrap a small hammer in a small towel. Gently tap the cat and if you hear rattles inside then you cat is bad. Its a pretty easy job to replace. I have had two go bad on me. I replaced it with one hand, literly.
See you at Bloomington, Vette on.
90 vetter
See you at Bloomington, Vette on.
90 vetter
Melting Slicks
Joined: Nov 2004
Posts: 2,799
Likes: 2
From: Cape Coral FL
Need to ask for some help.
Am from the C3 forum and over at my Brothers trying to help him track down a problem with his 90. His vette has been running well until it began to get sluggish. He took it to the shop and they are saying that cylinders 3 and 7 are not firing properly. Mechanic noted that the spark is fine, fuel pressure is good, no codes and he can hear the injectors working. But told my Brother to note that when he unhooks the injector wire...the idle doesn't change...so there is a problem with the injector.
This doesn't make sense...especially to me who is use to carbs.
Seriously... could really use some advice on what we can look at to try to narrow this down and fix. Day is almost over here in Milwaukee and we were going to take his 90 to Bloomington tomorrow for the weekend.
Thanks in advance... Ed
Am from the C3 forum and over at my Brothers trying to help him track down a problem with his 90. His vette has been running well until it began to get sluggish. He took it to the shop and they are saying that cylinders 3 and 7 are not firing properly. Mechanic noted that the spark is fine, fuel pressure is good, no codes and he can hear the injectors working. But told my Brother to note that when he unhooks the injector wire...the idle doesn't change...so there is a problem with the injector.
This doesn't make sense...especially to me who is use to carbs.
Seriously... could really use some advice on what we can look at to try to narrow this down and fix. Day is almost over here in Milwaukee and we were going to take his 90 to Bloomington tomorrow for the weekend.
Thanks in advance... Ed
Has the mechanic checked compression and/or leakdown on the suspect cylinders?
And something that can be really easy... are the #5 and #7 spark plug wires crossed? VERY easy for that to happen.
Cover the basics first before condemning the ECM.
Good luck!
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
Hi Bob,
The problem you currently have is that from 1989 through 1991 on the L98 engines GM installed Multec injectors. These injectors have one of the highest failure rates of any injector ever installed. It's not a matter of "if" they are going to fail, it's simply a matter of "when" they will fail. That is why some of your injectors look differently than the others. Some of them have obviously already failed and were replaced. Because of their design they cannot be repaired so the only solution is to replace them.
You can try to find some of the same injectors to use as replacements however they will likely eventually fail also so a better alternative is to replace them with an aftermarket set of replacement injectors or find some of the earlier Rochester injectors that were used from 1986 though 1988 on the L98's. These were a Bosch design injector and they don't have the problems that the Multecs do.
Sorry to be the bearer of bad news but that's just the way the Multec injectors are.
Hope this helps. Let me know if you need more info or have additional questions.
Rich Jensen
Here is a GM Service Bulletin on the same issue:
The good news:
1. Easy to check for problem.....you can do yourself!
2. Relatively easy to replace injectors.....you can do yourself! However, do not buy GM repalcements as you net worth will be reduced.
3. Cost will be about $325 for new injectors and gaskets.
Let me know if you need more info on this. BTW, the resistance spec is 16.5 +/-.3 ohms and all eight injector resistance should be close to the same value.
Suggest you review this thread on the same topic:
http://forums.corvetteforum.com/show....php?t=1727763
Let us know what you find on this
Last edited by Sam Lam; Jun 15, 2007 at 09:13 AM.
