engine accelerates and decelerates
Thread Starter
4th Gear
Joined: Dec 2002
Posts: 4
Likes: 0
From: corpus christi tx
engine accelerates and decelerates
hey guys need help, my engine accelerates and decelerates continueuslly when throttle is depressed upon taking off, if throttle is depressed slowly, no problem, this seems to happen only in 1st and 2nd gear, when cruising and throttle depressed, car runs ok when it kicks down to 3rd, when in drive and hand brake is on and foot brake held down and throttle depressed it accelerates and decelerates, have tried this in reverse with same senerio and it does not do it, other than that car starts, idles and cruises fine. thanks. :confused:
Burning Brakes
Joined: Mar 2001
Posts: 1,200
Likes: 0
Re: engine accelerates and decelerates (lcorvet)
Welcome to the forum.
check your vacuum lines, could be a leak somewhere. I had a car do this and it was related to the "idle up" for the ac.
Good Luck
[Modified by Rich_01659, 6:31 AM 12/24/2002]
check your vacuum lines, could be a leak somewhere. I had a car do this and it was related to the "idle up" for the ac.
Good Luck
[Modified by Rich_01659, 6:31 AM 12/24/2002]
Cruising
Joined: Dec 2002
Posts: 10
Likes: 0
From: Moreno Valley CA
Re: engine accelerates and decelerates (lcorvet)
It sounds to me like the Engine Temperature Sensor is bad. It is located on the front of the water pump and is very easy and inexpensive to replace. I have had this exact problem and the ETS was the culprit. Hope this helps.
Thread Starter
4th Gear
Joined: Dec 2002
Posts: 4
Likes: 0
From: corpus christi tx
Re: engine accelerates and decelerates (RubyRoger)
thanks for the info ruby, the engine actually accelerates and decelerates violently, almost to the point of dying if i don't put in nuetral, as i said thisonly happens in 1st and 2nd gear, under hard acceleration, is this what yours did?
Thread Starter
4th Gear
Joined: Dec 2002
Posts: 4
Likes: 0
From: corpus christi tx
Re: engine accelerates and decelerates (ittlfly)
the ecm send out a code 42 ( electronic spark timing circuit, EST), according to Recovering the C4 ECM Codes-www.C4vettes.com, possible failures,it says to check wiring at ignition module, replace ignition module, possible ECM failure. I check for loose wiring (OK), replaced the ignition module, still acts the same and still get a code 42. pulled complete distributor ,cleaned completely, checked all conections, all OK.
