so here is the issue i got the car running again after a transmission mishap and ever since now the motor is acting up. Its a 95 trans am lt1. i will start it, idles runs great until it gets to operating temp then when i give it slight throttle it stutters i try to mash the gas and bogs and stutters and a strong smell of fuel comes along too. also at idle it seems slightly rougher than normal. i found a messed up plug wire and fixed that hoping its the issue. now prior to any transmission work it ran great. has new head gaskets and intake gaskets, egr delete as well. all torqued to spec. the plugs are in good shape and wires are newer as well. not too sure about the 02 sensors though. i assume they are working ok since before i had no issues
please any advice or knowledge would be great i cant find another thread with similar enough problems that someone actually fixed

 

If you are smelling fuel then it is most likely missfiring and not burning all the fuel (no spark). But it's completely fine until warmed up, even driving it? Could be o2 related then because the o2's are bypassed for the first few minute as the car is in "open loop" before the o2's come to operating temp and start calculating the fuel mix. How long have you had the car? Could have more problems than you know like a shitty opti or something. REading you trans post it seemed like you haven't had the car long?

 

I'd look for an exhaust leak.

 

Do you still have catalytic converter/s on the car? The fact that it run great until it warms up wouldn't seem to point to a plugged cat, but it may be worth checking.

 

I put a new cat on the car not long ago and ya it idles and run good prior to warm up. I don't know the condition of the o2 sensors or opti and I know those can go out a lot

 

Also the ses light will turn off after I turn the car off and only sometimes will come back on when it does the car runs a lot smoother

 

What code for the SES? Did you check for exhaust leaks?

 

You've described at least 4 optispark symptoms so far, what opti are you running and how old is it? Any opti codes? (16, 36, and 42) Did they clean/degrease your engine or something when they put in the trans? (Got the opti wet??)

-sputtering
-weak spark (smells of gas)
-poor performance with car warmed up
-rough idle

 

So I don't have access to a scanner right now to read the codes I don't know what opti is in there came with the car I have done all the work myself I don't recall ever getting the opti wet at anytime since ownership

 

Did you check for exhaust leaks? Transmission work sometimes requires the y pipe to come off. An exhaust leak can cause exactly what you are describing. If you want to isolate the issue to the O2s disconnect them and see if the issue goes away. If it doesnt, it's opti or icm. If it does it's O2s, like an exhaust leak. With the SES light coming in and the issue going away I'd lean away from the Opti. Its likely going into open loop when the SES comes on.

Also, read this.

 

Bro, how would an exhaust leak cause that kind of issue unless the knock sensor is picking it up as false knock or something? If it was a bad enough leak that the o2's were thrown off by the mass amounts of exhaust flow missing, he would clearly be able to hear/find the leak. Yeah it could cause the smell, but I don't think an exhaust "leak" would cause the car to run like crap. By all means, please eplain to me how, because I am clearly missing something. Btw, my 93 and 94 both need opti's, and the CEL comes in and out occasionally. However, it doesn't seem to affect how it runs when it does; it's just sparraticaly random with no ill affects. And they run fine for a few minutes upon startup, then start to run like **** until the opti dries out. My 93 will run like **** after it rains for a half hour or more, but if I turn my manual fans on high it will clear up in mere minutes, every time. This confirms opti for me, and I have his symptoms including the random CEL/SES and car running fine until it warms up. BUT, only after a rain or something. But if his opti is in worse shape, everday conditions could affect it. But, I'm guessing that one or all of the o2's are messed up. It would be very easy to strain an o2 wire or bang into the sensor too hard or something while removing the tranny and mess em up, which is what I'm betting happened. My money is on o2 sensors. Matter of fact I recently helped a guy on youtube diagnose his 95, and the majority of the proplem was his o2's, with similar complains such as runs shitty and smells of fuel. He emailed me a data log and I could see the o2's weren't working properly and had him replace them and it fixed the problem. I'm betting o2's, especially after removing the tranny. I was just trying to say that these are opti symptoms as well, but in this scenario it seems highly probable it's the o2 system.

 

I'm guessing that one or all of the o2's are messed up. It would be very easy to strain an o2 wire or bang into the sensor too hard or something while removing the tranny and mess em up, which is what I'm betting happened. My money is on o2 sensors givin the scenario. Matter of fact I recently helped a guy on youtube diagnose his 95, and the majority of the proplem was his o2's, with similar complains such as runs shitty and smells of fuel. He emailed me a data log and I could see the o2's weren't working properly and had him replace them and it fixed the problem. I'm betting o2's, especially after removing the tranny. You can buy an obd1 scaner type thingy that plugs into the diagnostics port and just gives you the code number old school, with no explanation; just a number. Then you look up the code number. They start at like 30 bucks. I think it's just called an obd1 scanner. They sell them, but don 't have em behind the counter to check ur car for you, like they do with the newer cars. Autzone/Advance or the like. Keep us updated, I wan't to know how this turns out. You need to pull the codes and not waste money on guessing. But I will tell you, there are only so many things that can cause those symptoms, but on our cars there are a lot of them! MAF sensor, TPS sensor, opti, wires, plugs, coil, ICM, knock sensor, o2 sensors, ect. Basically anything that controls a/f ratios, or ignition. Code's gonna tell you where to look.

 

An exhaust leak pulls air IN to the exhaust as well as leaks air out. That fresh air gives a false lean condition. The O2s see this and richen it up, that would make it run like crap; missing, bogging, etc. But only when the O2s affect the AFRs; closed loop.

The engine requires certain coolant temps and run times to engage open loop. What he is describing can very likely be caused by exhaust leaks.

Also, he has a 1995 F-body, that means he cannot use OBD1 scanners due to the installation of the system by GM. He needs a 16 pin OBD2 plug for an OBD1 system. Hence the link I provided above.

That's why I keep asking about exhaust leaks. He has not addressed my question, likely for the same reason you think it's unrelated. Its very much related and can absolutely be the cause of the issue.

Too many times people ignore an exhaust leak only to end up with not only less performance but a bunch of other problems too. If it is exhaust leaks, it's certainly easier to fix that (and cheaper) than an Opti. Also, an opti problem will not care about open loop or closed loop. It'll run like crap regardless of what the O2s are doing.

That's why I recommended he disconnect them (the O2s) to see if the problem goes away. It isolates the problem and elliminates parts of the engine as potential problems.

I know your trying to help, as I am. But, maybe a bit more research is needed before you recommend he use equipment on his vehicle that doesn't work.

As for your issues, I recommend you pull the optis, disassemble and clean them, reassemble with sealant and loctite the rotor screws, reinstall with new vent lines, and make sure the ignition coil to distributor spark plug wire isn't touching the water pump. Then enjoy. Your opti works, just needs some basic maintenance, some gaskets, coolant, and time and you'll be back on the road without those plauging issues.

 

Well maybe a few guys on here know about the weird "off" year as you describe the 95 with the obd2 plug even though it's still obd1, but I don't really think most people will know that unless they own one so I don't feel bad for not knowing that. Everyone knows obd2 started nationwide in 96, so I don't feel retarted for not knowing about the 95 obd1/obd2 thing. But thanks for sharing that, I love learning about these cars. And I am trying to help with the knowledge that I have of these cars having owned 4 of them (but never a 95+). I'm not trying to do hours of research for someone that should have done that themselves. I'm only speaking off of what I already know. And I have a question about that 95. On the 93 and 94 you can delete the cat and not get a CEL because it's obd1, so can you do the same on the 95 without throwing a CEL since it's still technically obd1? And maybe you should take your own advise before offering ME advise about my opti's and "do more research" yourself. "Reinstall with new vent lines"... The 93 and 94 as I stated I own do not have vent lines

 

Yes, you can delete the Cat without getting an SES code.

The 93-94 LT1's did not have the Vent, I know that already. There's a reason I said 'reinstall with new vent lines". Because if it has them, it's likely due for some none dry rotted ones. If it doesn't have it, it needs it. It doesn't matter what year you have, Vent lines are a must and most of them are dry rotted from being installed for 20+ years. I may have been addressing you with my advise, but it wasn't intended for just you. It was intended for anyone else reading our conversation too. There's a reason GM installed the Vent lines after only 3 years on the market, it's the same reason you should already have them. You having owned 4 LT1 F-Bodies, I guess it was wrong for me to assume you did the vent line mod; my bad. Most Opti's that are replaced, aren't bad. They may be dirty, have a bad cap and rotor, or need re-sealed. But people replace them anyway because it's assumed the Opti is bad, not dirty or something else simple or cheaper. I'm not saying Opti's don't go bad, they do. But it's not as common as their replacement rate is.

 

Well you saying I should have done the vent mod is your own opinion. There are several reasons to NOT do the vent mod, just as there are reasons TO do the vent mod. And I am well aware that you do not have to necessarily replace the whole opti unit when it starts giving you problems, but honestly I think in most scenarios it is the best idea. Why? Pull it apart, clean it, put a new seal in it, put a new cap and rotor on it, done. Then a few thousand miles later the optical eye goes out on you or something else and you have to replace it anyway. The service life of an opti is less than 100k per GM ( ), so cleaning it up and throwing a new cap and rotor on it will only last so long. The opti will fail eventually. If short on cash, sure do that. If you're not keeping the car for the next few years, sure do that. Otherwise, you will be replacing that opti eventually so why not do it once? And what you say about the exhaust leak sucking in air and making a false lean makes sense, but I wouldn't figure it to make the car run that bad? I'll take your word on it though, I'm not disputing that. You sound like you have some experience with that fiasco. Nice to know for future reference. Oh and I'm pretty sure he can still get a scanner thing for his weird 95 obd1/obd2 delema. He just needs an obd2 connecter to go with the obd1 scanner, swap em out. I only mentioned it because depending on which model you buy, they literally start at 30 bucks, or cost as much as 200+.

 

i was finally able to pull the codes and its code 44 o2 sensor running lean on left bank gotta do some research tonight if you guys ave any ideas as well please feel free to let me know

 

Read this, about dignosing that code: http://www.misterfixit.com/code44.htm Please let me know if this helps. Of course, it could just be a bad o2, but that link shows you what to check before replacing it, without me having to type it

 

Maybe I'm just lucky. I disassembled mine and cleaned everything good. I bought a cheap chinese opti and transferred my original mitsu sensor to the new opti, as mine's bearings were shot. I did this almost 5 years ago. So my "optical eye" is still going strong after 190k in an unvented oti. I just replace the cap and rotor and inspect every few years, but like I said, maybe I'm just lucky.


Now that I've said that, I expect my sensor to die sortly

 

well at least you have it narrowed down to a specific bank. check all the plugs, wires, and injectors on that side. The computer is probably seeing extra oxygen from a misfiring cylinder and dumping extra fuel in that bank to compensate.