85 with hesitation
Thread Starter
3rd Gear
Joined: Apr 2007
Posts: 3
Likes: 0
85 with hesitation
I started this once and musta hit send or something and lost what I wrote, sorry bout that. Anyway, I'm a newby and have really enjoyed reading all the posts and responses.
My 85 hesitates on acceleration. I've read about others who have this similar problem. I replaced the TPS a coupla years ago and it seemed to correct it some. Then late last year before I put it away for the winter, it started again only worse. I have a friend who experienced this same problem a few weeks ago, and it was his ECM. Once he changed it, the car ran great. I checked the TPS setting and could not get a reading under 4.6 volts. When I installed it I had it set right at .54. I put the old TPS in just for the heck of it, and got the same readings. When I checked the codes I got 21 and 22. When I reset I got 21, which says the ECM and wiring are good, bad TPS? Also when I plugged the clip into the plug to check the codes my radiator fan came on??? Didn't expect that . So should I throw in another TPS, or am I overlooking something? I hate to just keep throwing parts in till the problem is solved. What do you think?
My 85 hesitates on acceleration. I've read about others who have this similar problem. I replaced the TPS a coupla years ago and it seemed to correct it some. Then late last year before I put it away for the winter, it started again only worse. I have a friend who experienced this same problem a few weeks ago, and it was his ECM. Once he changed it, the car ran great. I checked the TPS setting and could not get a reading under 4.6 volts. When I installed it I had it set right at .54. I put the old TPS in just for the heck of it, and got the same readings. When I checked the codes I got 21 and 22. When I reset I got 21, which says the ECM and wiring are good, bad TPS? Also when I plugged the clip into the plug to check the codes my radiator fan came on??? Didn't expect that . So should I throw in another TPS, or am I overlooking something? I hate to just keep throwing parts in till the problem is solved. What do you think?
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
First, you need to find out what is causing the code 21. Then I would suggest you change the fuel filter, pvc valve, and attach a fuel pressure gauge to the schrader valve and check fuel pressure while driving. Perhaps and overall tune up.
Thanks to AGENT 86:
http://members.shaw.ca/corvette86/Code%2021.pdf
Thanks to AGENT 86:
http://members.shaw.ca/corvette86/Code%2021.pdf
Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
FSM by helmsinc.com will be your best frend:
The search function will help
here is a link on codes and diags: http://www.troublecodes.net/GM/
yes, fan comes on when is diag mode for codes
The search function will help
here is a link on codes and diags: http://www.troublecodes.net/GM/
yes, fan comes on when is diag mode for codes
Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
First, you need to find out what is causing the code 21.
Thanks to AGENT 86:
http://members.shaw.ca/corvette86/Code%2021.pdf
Thanks to AGENT 86:
http://members.shaw.ca/corvette86/Code%2021.pdf
As EFI-CFI would say, don't shoot the messenger. A TPS code does not necessarily mean the TPS is bad.
Thread Starter
3rd Gear
Joined: Apr 2007
Posts: 3
Likes: 0
Been outta town and haven't been able to put the time in on the car. I got the TPS set right, then no codes came up. This was good. I was still getting the hesitation now with a back fire! I knew then that I had an ignition problem. Long story short. I replaced the plug wires and it runs better than it did in '85. You guys were all great with your quick replies and your tech advise was top notch. Thanks for all your help and being there for a fellow vetter.
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