Posted 12 March 2003 - 01:59 PM
I just found this great site and was hoping some of you experts could give me a hand.
I'm having a problem with a friends pickup truck. It's really a 90 GMC Sonoma, but it's the same as a S10 and everytime I get parts they never have a good listing on the Sonoma so I always tell them it's an S10.
Anyway, here's my problem.
After this truck warms up it has no throttle response in the upper rpm's. The truck will idle but when you give it gas to go it just bogs down and falls on it's face. If you race the crap out of it, it will eventually go. This truck has about 110,000 miles on it. I did a full tune up six months prior and it was running great. Now after this problem started I tried to retrieve a code without any success. The check engine light would come on but it would go back off and not store a code. I used an auto x-ray to try and get the codes. Having no idea what the problem was I started with the little things. First I changed the O2 sensor and then the TPS sensor (TPS is set properly). This didn't fix my problem. I had the owner of the truck run it out of gas and then refuel it, just in case it was a bad fuel issue. He refueled and the problem was still there. I changed the Fuel filter again just in case. I then checked again for codes and got a Code 42 which put me towards the Electronic Spark Timing. The book said it could be the module so I decided on a rebuilt Distributor so I would get a new module and pickup. I also changed out the coil. Well, my problem is still here. I jumped out pins A&B on the Diag plug so I could set the timing to 8 Degress as required. When the jumper is out of the diag plug I have 35 degrees advanced timing according to my timing light. Is this normal? Also, when I drive the truck it's pinging like crazy when you try to give it gas. I was reading a little more and it says that the ECM controls the spark timing along with the Distributor. Well, since I already changed the Dist, could this be an ECM problem? Are the computers know to go bad in these 2.5 4cyl pickups? Are there any common problems I should know of? Are there any other common sensors that control this that may have gone bad?
I need your help. I've just about given up.
Thanks for any help you can give me.