QuestionVan,
This weekend I replaced the coil, egr valve. Cleaned the distributer which seemed to have quite a bit of build up for less than a year old. Did not solve the problem. I then replaced the distributer & rotor as well as two oxygen sensors (did not realize there were 4 and auto part store closed). Truck ran great for two days. Now, it seems to have a cough or sputter sometimes between shifting gears and sometimes while driving on the highway when needing to accelerate.
Should I replace the last two sensors or do you think my problem is somewhere else?
Mike
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Followup To
Question -
Van
I noticed this e-mail.
Expert:Van
Date:4/26/2004
Subject:Missing 5.7 Vortec
Question
I have a 1996 Chevy 1500 Z-71 with a 5.7 Vortec, 5 spd.transmission. Whenever it rains or the air is very damp, i.e. heavy fog, the engine misses at normal load/speed, at about half throttle. It runs fine at full throttle or idle. A local mechanic ran a diagnostic on it and it came back as a misfire code. He advised me that it was probably an ignition problem, most likely a spark plug or plug wire. I replaced the plugs, wires, dist. cap and rotor button about 15,000 miles ago.
What should I check and how do I check it? You can give it any amount of gas while sitting still in neutral and it doesn't do anything, just when you're actually driving... Any help on this matter will be greatly appreciated.
Craig Sykes
Did you get a response back on this? Because here is my problem.
I have a 96 Silverado. Vortec V-6 4.3L.
At speeds of between 70 to 80 it seems to cutout or mis-fire. I don't loose RPM's and I don't loose speed. It does not do this while accelerating or when going up hill, just at cruising speeds. It use to do this only when wet conditions.
I got a code about 1 & 1/2 years ago for the EGR valve. I replaced the valve. I think soon after this problem showed up. I got a code about gas cap not sealed right. Reset computer and got the code again. I replaced the cap and reset computer and seemed to stop the code. But still had theses symptoms when wet.
Then I got a cylinder hesitation code and I replaced wires, rotor & distributer cap last summer and it seemed to haven taken care of the problem but only to return this winter. It now does this everytime I drive the truck.
I have also replaced the fuel filter, plugs and used fuel treatment as well. Any Ideas?
Answer -
And Mike,
I would probably unhook the control to the EGR valve, just to see if that helps. It might set a code, but you apparently have a way to clear it.
Van
AnswerHi Mike,
I see that you have replaced the fuel filter, but have you checked the fuel pressure with a tester?
I would suggest that, and if you can see the pressure tester while driving, see what it does during the sputter. it should stay right at spec pressure, not drop.
Throttle position sensor is another cause of stumble during acceleration, or under load, but sounds like yours is just cruising.
I have heard of people cleaning the mass airflow sensor, but I have never done it.
If you go to the following link, and do a search for MAF sensor, for the past six months, you should see some posts. It is a very good forum site for Chevy owners, and is free.
www.chevytalk.org/
Van
