When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello, I just bought a 1995 6 speed, really nice car. It has 134k miles and I do not know the service history. The car is experiencing hesitation when accelerating, down on power, running very rich, poor mpg, backfiring around 2-3k RPMs, and a slight tick in the motor. I was told the car had cats but when I fixed an exhaust leak I discovered it didn't have any cats or mufflers (It's very loud). I've read a lot of potential causes including a bad optispark, MAF sensor, computer, o2 sensors, etc. I don't have the most money to throw at the car because I just bought it so I'd like to narrow the issue down. Any advice would be great. Thanks.
Start by pulling the codes, you don’t need a reader just a paper clip. Search for “paper clip read codes” in the forum.
post what you find here
okay I ran the codes and received quite a lot H72, H16, H26, H32, H43, H48, H63, and H65. After copying down the codes I cleared them, started the car and let it idle for about 5 minutes. Afterwards the codes I received were C72, H72, H26, H43, and H65.
okay I ran the codes and received quite a lot H72, H16, H26, H32, H43, H48, H63, and H65. After copying down the codes I cleared them, started the car and let it idle for about 5 minutes. Afterwards the codes I received were C72, H72, H26, H43, and H65.
You and I are in a very similar situation! I just picked up a ‘95 with a 6-speed and unknown service history. Mine is hesitating/sputtering under heavy acceleration after warmed up. I’m currently working on replacing O2 sensors, plugs, and wires based on it running rich as well as throwing a few codes.
okay I ran the codes and received quite a lot H72, H16, H26, H32, H43, H48, H63, and H65. After copying down the codes I cleared them, started the car and let it idle for about 5 minutes. Afterwards the codes I received were C72, H72, H26, H43, and H65.
Need to know WHICH MODULE those codes relate to, can't just take it that they will be engine diagnostics related.
Any code with an H means it has been and gone, doesn't mean the problem may not still exist, but it isn't C, so it isn't current.
We can't do anything with that C72, because you do not say which module it is from. It could be a serial data link error, it could be a gear selector switch error, it could be a loss of VSS signal, those are all DTC72
You and I are in a very similar situation! I just picked up a ‘95 with a 6-speed and unknown service history. Mine is hesitating/sputtering under heavy acceleration after warmed up. I’m currently working on replacing O2 sensors, plugs, and wires based on it running rich as well as throwing a few codes.
Here’s an explanation for the codes.
Hold on, this a a very incomplete guide and missing a lot of critical info.
It is extremely important you know which MODULE the DTCs are from before you can search up on what they might relate to.
Need to know WHICH MODULE those codes relate to, can't just take it that they will be engine diagnostics related.
Any code with an H means it has been and gone, doesn't mean the problem may not still exist, but it isn't C, so it isn't current.
We can't do anything with that C72, because you do not say which module it is from. It could be a serial data link error, it could be a gear selector switch error, it could be a loss of VSS signal, those are all DTC72
ok I believe the first c72 and h72 codes were from module 1. The rest were from module 4 besides the H65 which was from module 9.
ok I believe the first c72 and h72 codes were from module 1. The rest were from module 4 besides the H65 which was from module 9.
I don't have a 1994 or a 1995 service manual handy at the moment, so i can't locate all the codes for you.
DO NOT just go by generic codes, they may or may not be correct, some of those DTCs varied between some years, so the codes MUST be for a 1994 or 1995, which are both the same in terms of function.
Module 1 is CCM, and that code could be something as simple as the dimmer failed or the factory radio headunit has been replaced. I can't confirm that accurately, i don't have the correct manual here.
Module 4 is for the engine, i do have a list for those. H16, Distributor Ignition System Low Pulse - common with some aftermarket distributors.
H26, Evaporative Emission Canister Purge Solenoid Valve Circuit - I believe this is an OBD2 code and won't set the check engine light, need the manual to confirm.
H32, Exhaust Gas Recalculation - pretty self explanitory, check the EGR setup.
H43, Knock Sensor Circuit - again, check the wiring and make sure nothing shorted or burned.
H48, Mass Air Flow Sensor Circuit - this one could cause your issue, need to follow the 94/95 manual diagnostic procedure
H63, Bank 2 RF Heated Oxygen Sensor #1 Circuit Open. - This will also cause it to run rough. Check the wiring and maybe consider swaping the sensors around. There is 3 O2s in a 94/95, the secondary sensor is not used for AFR corrections and is part of the OBD2 setup, which on a 94/95 will not set a check engine light if removed or unplugged, so that could give you a spare to test with if the 3rd sensor is still there.
Module 9 is ABS/ASR, if the battery was low at some point you may get codes in Module 9 that were due to low power.
Focus on Module 4 DTCs for now, then move forward from there.
If anyone has any similar issues I wanted to let everyone know the problem has been found. After breaking my optispark and completing redoing the front of the engine, it did not run any better. still, no power, sputtering and backfiring like crazy. Well, it was a collapsed lifter. Fixed that and the car runs great. Hope this helps anyone.
I am not sure if my 92 has this same issue. I posted a while back about it. My car feels like a turbo vette, but it is stock (no forced induction). It runs smooth. No codes. No tick in the engine. When I accelerate it feels strong but at 3500 RPM it gets a boost. I have 185k miles on mine. I am in the process of doing the timing chain. I am also pulling the intake manifold to address the leaky china wall. Was the collapsed lifter obvious? I would like to check all of mine while I have the intake off.
Yes, the lifter was quite obvious when I saw it at least lol. As I mentioned I had just done an overhaul of the front of the motor with new gaskets, optispark, water pump, coil, etc. After I got it running, it still had the same issue and decided to pull off the valve covers. Immediately I saw a push rod out of place and no lifter to support it. I'm not exactly sure whether that is a collapsed lifter or not, but I found the top half of the lifter in the valley pan and the bottom half still in the slot. I bought a single, new lifter and installed it and it seems to be running great. Now with your "boost," I'm assuming you got the car second hand, and correct me if I'm wrong, it may be a cam? possibly a cam that's meant for higher rpm performance or something of the sort, I don't know much about them but if I were you I'd definitely look into it.
I just got mine this past October with about 184k miles on it. I've put about a 1000 miles on it (500 was the drive home). I don't think it has a performance cam as it has a really smooth idle. Any cam that starts making power at 3500 would have an extreme lope. I decided to go ahead and just replace all the lifters. After researching worn lifters I've come up with the possibility that as these lifters have so many miles they may have lost some of their tension. After higher RPMs they may gain that tension back. Now I have ran into the problem of getting them. Autozone has the Melling lifters as the only ones they carry. They only had 4 in stock and they were a made in China no name with the same part number JB2079. So they ordered me 12 more from the hub. I got those today and they are Made in USA Melling. So I asked them to order 4 more. The hub only has 3 in stock. So they ordered those and are trying to locate another actual Melling lifter from another supplier. Everytime I work on this car I end up having it down for a couple weeks while I chase and order parts.
LT1 Running Rough
