misfire under load - Page 3 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 05-09-2003, 12:32 AM   #21
Senior Member
True Car Nut
 
Join Date: Sep 2002
Posts: 3,392
Thanks: 0
Thanked 0 Times in 0 Posts
fuddyduddy121 is on a distinguished road
Default

Quote:
Originally Posted by UserBrett
Quote:
Originally Posted by fuddyduddy121
If the same problem seems to happen at the same throttle angle every time, it'* possible you may have a dead spot in the throttle position sensor, and it may need to be checked. The easiest way to do it is with a Tech 1. Move the throttle sensor slowly from idle to wide open and see if there are any jumps, or if the resistance increases in a uniform fashion. You can also do it with a multimeter too.

Is it also possible you could have a bad fuel injector?

Just an idea if you've tried everything else.

Quote:
Originally Posted by UserBrett
Car starts fine, Idle is fine,Runs good until load and boost and low rpms
but can get the problem in 3 going up a hill but a lot harder to do.
Injectors rebuilt and tested,
new coils,icm(used),maf,map,fuel filter,nose cone,sparks plugs(2 sets),wires,
orderedO2(comming soon, Delco. I dont think this will help).
No back pressure problem.
?
The Funny thing is I unplugged the MAP sensor with no difference in the problem,
so I got a new one. No change.
The throttle is fine. Smooth change in voltage Wide open reads 4.08 v
Should this be closer to 5v?

Could be the injector but had them tested.
Sounds like it is fine, it really is not supposed to go over 4.1-4.2. The key was to check for dropouts on the way from low voltage to high. How did you test the fuel injectors?
fuddyduddy121 is offline   Reply With Quote
Old 05-09-2003, 12:52 AM   #22
Junior Member
Posts like a V-Tak
 
Join Date: May 2003
Posts: 29
Thanks: 0
Thanked 0 Times in 0 Posts
UserBrett is on a distinguished road
Default

Quote:
Originally Posted by fuddyduddy121
Quote:
Originally Posted by UserBrett
Quote:
Originally Posted by fuddyduddy121
If the same problem seems to happen at the same throttle angle every time, it'* possible you may have a dead spot in the throttle position sensor, and it may need to be checked. The easiest way to do it is with a Tech 1. Move the throttle sensor slowly from idle to wide open and see if there are any jumps, or if the resistance increases in a uniform fashion. You can also do it with a multimeter too.

Is it also possible you could have a bad fuel injector?

Just an idea if you've tried everything else.

Quote:
Originally Posted by UserBrett
Car starts fine, Idle is fine,Runs good until load and boost and low rpms
but can get the problem in 3 going up a hill but a lot harder to do.
Injectors rebuilt and tested,
new coils,icm(used),maf,map,fuel filter,nose cone,sparks plugs(2 sets),wires,
orderedO2(comming soon, Delco. I dont think this will help).
No back pressure problem.
?
The Funny thing is I unplugged the MAP sensor with no difference in the problem,
so I got a new one. No change.
The throttle is fine. Smooth change in voltage Wide open reads 4.08 v
Should this be closer to 5v?

Could be the injector but had them tested.
Sounds like it is fine, it really is not supposed to go over 4.1-4.2. The key was to check for dropouts on the way from low voltage to high. How did you test the fuel injectors?
Had spray pattern and M/*-RPM all passed before and after cleaning. Flow rates about
74 Pressure seatting 74 @(could be a c)40F
Injector # 0280150934 Bosch
UserBrett is offline   Reply With Quote
Old 05-09-2003, 12:55 AM   #23
Burgundy_Boat
Guest
 
Posts: n/a
Default

hmm... Bosch... is it just me or do i smell a rat??? is a boche anything not good for our cars or is it just the plugs and wires?
  Reply With Quote
Old 05-09-2003, 12:54 PM   #24
Senior Member
Posts like a Turbo
 
Join Date: Mar 2003
Location: Indianapolis, Indiana
Posts: 311
Thanks: 0
Thanked 0 Times in 0 Posts
along is on a distinguished road
Default

I dont know about Bosch, but every mechanic i have had said to use AC Delco parts.

I do know that even after removing the Bosch plugs, the new plugs didnt make any difference.

After reading tons of messages about this, I get the feeling that the ignition/fuel fault finding is a rogue symtom and we are trying to fix the wrong thing.

The TCC solenoid in the Trans that locks it into overdrive sounds a good fit. If it is slipping, that could cause my lower economy on the highway, the slipping could make it feel like the engine is missing. And it sort of did start to happen around the same time my trans started making a sort of squeeking/chirping noise when slipping into OD/ or under acceleration in OD.

Any thoughts on this ?
along is offline   Reply With Quote
Old 05-12-2003, 10:45 PM   #25
Member
Posts like a V-Tak
Thread Starter
 
Join Date: Sep 2002
Location: Chicago, IL.
Posts: 33
Thanks: 0
Thanked 0 Times in 0 Posts
t-type is on a distinguished road
Default

I have fixed it!

As you may last recall I had just reinstalled the fuel injectors after having pulled them to inspect them. The car ran worse when I started it. I double checked my work and all was good. So I used a favor and borrowed a scan tool (no, I wans't ignoring you fuddyduddy121). It told me that #5 was a weak cylinder. I pulled the plugs again and 5 out of the 6 looked the same as before. But #5 was completely fouled up. I had done a spark test so I knew the spark was good. So even though the injector ohmed good I replaced it anyway. Now it runs great!
t-type is offline   Reply With Quote
Old 05-12-2003, 11:44 PM   #26
Junior Member
Posts like a Ricer Type-R
 
Join Date: Aug 2002
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
willwren is on a distinguished road
Default

Damn! it'* about time! Glad to hear it. Those little damn things can get the best of us. Probably 95% of the problems here are a tuneup item.
willwren is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
help...my car has a misfire under a hard load SSEi93 1992-1999 1 05-15-2008 03:37 PM
1997 LeSabre - CYLINDER 6 MISFIRE - bucking, under load, etc Andx0r Buick 4 03-23-2008 01:59 AM
very bad misfire under load (93 SE) (SHES ALIVE!) Lowrider0308 1992-1999 13 09-07-2007 05:36 PM
Update: figured out popping under load in all gears/misfire Brian95Blown 1992-1999 6 11-30-2004 07:02 PM
Misfire under load 50 + mph Brian95Blown 1992-1999 2 06-23-2003 03:47 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 01:24 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.