1995 C4 Please Help!
Thread Starter
6th Gear
Joined: Dec 2012
Posts: 6
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1995 C4 Please Help!
I have a 1995 C4 that was missing at stop lights and then became very hard to start. Took it to a shop to see what codes were being displayed, the guy said that I had fuel injectors problems. I replaced all the fuel injectors didn't help. Replaced the MAP,coil,idle air flow module,IAC,TPS,spark plug wires, opi-spark, temperature sensor,check the fuel pressure and now it runs like it is too far advanced, will not idle and pings at any engine speed and has a terrible miss All wire are on the right plug. All sensors were replaced no vacumn leaks. The only parts not replaced were the 02 sensor and the knock sensor. The mass air flow meter was replaced about a year ago as well as the fuel pump and the EGR. Any ideas?
I would throw more parts at it but I cannot think of any other parts to throw at it.
I would throw more parts at it but I cannot think of any other parts to throw at it.
Race Director
Joined: Dec 2006
Posts: 10,383
Likes: 4
Disconnect the coolant temp sensors, knock sensors, o2 sensors, MAF, and the vac line to the FPR.
Will the car start and idle smoothly when you force it to remain open loop?
Did all the sparkplugs look similar when you changed them?
Did you verify the primary ignition wires? check for spark leak using spray bottle and engine running in dark?
Did you pull your own codes? (really easy with a paper clip will link for you if needed.)
Verify the grounds?
Will the car start and idle smoothly when you force it to remain open loop?
Did all the sparkplugs look similar when you changed them?
Did you verify the primary ignition wires? check for spark leak using spray bottle and engine running in dark?
Did you pull your own codes? (really easy with a paper clip will link for you if needed.)
Verify the grounds?
Thread Starter
6th Gear
Joined: Dec 2012
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Check grounds
yes I have check all the grounds in fact I went through the complete wiring harness and took all the inter fenders apart looking for a ground problem, checked everything unpluged all conectors and check and clean them.
I will try unpluging all the suggested items tomorrow and see what happens. At least with the new opti spark it starts easy, but it sure misses and pings. Thank you for you responce.
I will try unpluging all the suggested items tomorrow and see what happens. At least with the new opti spark it starts easy, but it sure misses and pings. Thank you for you responce.
Burning Brakes
Joined: Mar 2012
Posts: 769
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From: California
FL Events Coordinator
St. Jude Donor'13
I have an 89' corvette that had a bad oxygen sensor when I got it due to sitting for at least 3 years. Had almost all the same symptoms like bad idle and missing. Replaced it and it was fixed.
I also had a fuel pump failing not to long ago and had the same issues like hard starting and not wanting to idle. It would try and die if I was not giving it gas at all times.
Hope this helps, Stephen
I also had a fuel pump failing not to long ago and had the same issues like hard starting and not wanting to idle. It would try and die if I was not giving it gas at all times.
Hope this helps, Stephen
Thread Starter
6th Gear
Joined: Dec 2012
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It turns out that after replacing everything as mention above the car has blown head gaskets. Common problem on lt1 engine. Never overheated and has only 50,000 miles on it. Took the heads off and sure enough blown head gaskets.
Safety Car
Joined: Sep 2010
Posts: 3,752
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From: Indiana PA
Blown head gaskets on LT1's are not that common. Blown head gaskets on Nissan 1.8L 4 cyl. now those are common. Seems about every other week one is in the shop.
Wow, you spent a TON of money to fix blown head gaskets.
Diagnosis is the operative word. Its not that hard. Besides you learn stuff by doing it.
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Racer
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From: Huntsville AL
Race Director
Joined: Jan 2005
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From: Slidell Louisiana
Blown head gaskets on LT1's are not that common. Blown head gaskets on Nissan 1.8L 4 cyl. now those are common. Seems about every other week one is in the shop.
Wow, you spent a TON of money to fix blown head gaskets.
Diagnosis is the operative word. Its not that hard. Besides you learn stuff by doing it.
And unless you are the original owner you don't know if its overheated or maltreated..
MIke
Thread Starter
6th Gear
Joined: Dec 2012
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Yes you are are all right.That is what I get from using the scan tool, I should have gone off my basic instinks. I was getting all kinds of different codes - non of which were the problem. When I 1st started having problems I took a good look at everything including the oil cap, saw a little oil and water mix on it but the crankcase oil was clean.
In the past I would have looked into a cooling system problem, but instead I used the scanner. I discovered the blown head gasket when I removed the o2 sensor and ran the engine and saw steam coming out of the o2 hole. Next time I will still scan but go on past experience and logic to determine the problem.
Great web sight got a lot of information from it. Keep up the good work.
In the past I would have looked into a cooling system problem, but instead I used the scanner. I discovered the blown head gasket when I removed the o2 sensor and ran the engine and saw steam coming out of the o2 hole. Next time I will still scan but go on past experience and logic to determine the problem.
Great web sight got a lot of information from it. Keep up the good work.
Race Director
Joined: Jan 2005
Posts: 10,641
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From: Slidell Louisiana
Thanks for posting the final diagnosis.
95-96 LT1s are a pretty reliable piece of kit. The engine electronics are the same as the Caprice/Impala and they were known for going hundreds of thousands of miles.
Good luck with the gasket change. Shoot I just reread your post are both gaskets blown??? If thats the case something may be up, ensure gasket mating surfaces good to go. IE flat no cracks etc
95-96 LT1s are a pretty reliable piece of kit. The engine electronics are the same as the Caprice/Impala and they were known for going hundreds of thousands of miles.
Good luck with the gasket change. Shoot I just reread your post are both gaskets blown??? If thats the case something may be up, ensure gasket mating surfaces good to go. IE flat no cracks etc
Last edited by aboatguy; Jan 23, 2013 at 07:57 PM.