Rough idle and then won't start

[louie43]

I have a '97 GSX that suddenly started running rough at idle. It is not modified at all (yet). I had filled up on 93 octane like I have 20 times before from the same station and it was running fine. I stopped the car and restarted it 3 times over the next 6 hours (lunch, home, store) and that is when I noticed a rough idle. I finally went out to start my car to go home and it would not. All fuses are fine. I pulled the plugs and they were covered in fuel. Bought new plugs, put them in and tried starting it. Same result, covered in fuel. Pulled a plug and checked for spark, plenty. Thought maybe bad gas, pulled the fuel line from the fuel rail, pumped gas into a bottle, walked out and dumped gas on sidewalk and tried to lite it. Lit up fine. So, too rich of mixture 'cause by a bad O2 sensor? Never knew one would go out that fast. Maybe still bad gas but it burns with open flame? Hate to drain 14+ gallons of gas if it isn't the issue but will do that next. I can always use it in the lawn mower or pour it back in. Any other suggestions?

 

[oddrob]

Did you check all the connectors to the sensors under the hood? MIght be that simple.

 

[laser5spdturbo]

sounds like a bad o2 sensor

 

[louie43]

Well, replaced the O2 sensor, same issue, nothing has changed. There's $89.00 for the hell of it. Draining the tank tomorrow.

 

[twenty5psi]

Well, replaced the O2 sensor, same issue, nothing has changed. There's $89.00 for the hell of it. Draining the tank tomorrow.

Not really..Just take the old one and put it back in and save this one until the old one kicks the bucket if the old one performs the same as the new one..It'll die eventually,trust me..Unless it is fairly new itself..

 

[louie43]

Well, I have drained all the gas out of the tank and fuel lines and replaced with Ultimate fuel. (If you need help with pulling the fuel pump and float I got that down) Same result, turns over but will not start. After I pull the plugs and clean them, I might get one pop, like it fired and then nothing. When I pull the plugs, they have fuel on them. If this is an air/fuel mixture issue, where else can I look to figure out why this is acting this way? Mass Air Sensor? Or might it be the timing, the crank sensor? Firing late. I am going to try and turn it over with the timing light on to see if the timing is off. I am frustrated as can be right now and close to just buying a sensor/computer diagnostic tool. Guess I'll check these forums for the one rated the best. My older American cars are easier to diagnose than this.

 

[16g-95gsx]

Being a 2g your base timing is already done for you, it is electronically controlled. That isnt the issue.

Are you absolutely sure that you are getting spark? There are only 3 things that make am motor run, we all should know this. You obviously are getting one of them, start running through the system and diagnosing the other two. Are any 2 cylinders noticably more fouled than the other two?

 

[louie43]

Thank you for the reply and saving me a few hours of wasted time. I tested all four plugs and I am getting spark out of all four, yes. When I pulled the original plugs, they were all a little black, about the same across the board. Not sure how many miles were on them, 2nd owner. I have replaced them with the Platinum Bosch plugs. Now when I pull the plugs after trying to start it, they are damp with fuel. Air flow is not restricted, fuel pump works, it's getting spark yet it won't run. Only thing I can think of left is the MAS. I have seen in other threads that this can be disconnected and the computer will go to a default setting. I'll look up where it is, unplug it and try it tonight. I am still open for more ideas.

 

[louie43]

I give up. I am taking it to the dealer but he is booked for two days. Hmm, pattern? I don't get it because I have a 1992 TSi and I have put 199,000 miles on it with very little issue (even original clutch). Yes, I could change the timing belt in my sleep now. I only have 80K on this '97 and I have went 2+ weeks without it already. When I learn of the culprit, I will let you all know. Just can't believe no one has had this issue on here before.

 

[louie43]

Well, I gave up and took it to the dealer. The car has 82K miles on it. Right off the bat, the service guy cranked it and said it was the timing belt. I thought, can't be. I replaced it at 75K (when I purchased it from the previous owner). So I got the 10MM socket out and took the timing cover off.... IT WAS OFF!!!! Slack in the belt, the tentioner FAILED! When I changed the timing belt I had to fight that thing to get it down so I could put the pin in to put it back in. When I pulled the pin, it snapped up pushing the belt tight. Felt the piece had a lot of life left in it. I didn't have to replace the tensioner in my '92 until 131,000 when I did that belt so I thought it would be fine. Ran it to 199K so far and it is STILL good to go. SO, I am waiting on a call to hear the exact damage. Being off, he said that the chances are high that the valves are either bent or broke. I never heard anything of the sort when it wouldn't start. I am frustrated and flat out pissed off. My only advise is that when you change the timing belt and balance belt, replace that weak POS too. Whether it feels weak or not!

So, next question. If I have a damaged head, what's the best aftermarket head out there or go stock?

 

[dentman]

I just finished fixing a 1G engine with a skipped belt and bent intake parts.

I suggest that you do a leak down test now to see if the intake and/or exhaust valves are bent. If the timing belt has skipped a lot, you will have a major engine repair to do. If this is so, then you should remove the head and assess whether to fix it or put on another one. You car has low miles, so I'd probably fix the head if it's not too badly beat up. That way you know what you are getting put back in your car.

My 2 cents.

Dentman

 

[louie43]

I am having a dealer do this work for now. He seems to be knowledgable and honest so far. I have a few decisions though. This happened while trying to start the car so I can't imagine there being that much damage but knowing my luck, it'll be the worst case senario he's ever seen. He said after looking at it with a scope, looks like only the exhaust valves are damaged.
So, rebuild the head or new Head with new valves, valve guides, etc?
If the pistons are damaged, rebuild or get a whole new engine?
If I am up to about $2,000 now, might as well see about a whole new engine. Saw some remanufactured by Jasper Engines when I was looking to do the '92. Might look into that with a little more seriousness now.
Maybe a stroker like I have seen on these pages? I would like to get more HP out of the car and now seems like the better time to do so. I still don't get how my '92 TSi I can take care of it, run 199,000 miles without this kind of issue and this one pukes on me at 82,000.

 

[louie43]

Well, the top section of the engine is off. Looking inside the intake and the throttle-body, they were as dirty as can be. That valve cover hose for the oil smoke is getting capped with a breather that's for sure. The pistons had carbon all over the tops. The cylinder walls were nice and smooth though, no scoring and no ridges. The head is getting repaired at the machine shop, all new valves, both intake and exhaust. Whole thing is going to cost me (est) $1,800. Found out having the machine shop replace the valves was cheaper than having the dealer do it. I understand it is being done by one of the best machine shops in Indianapolis that also do work for some racing teams here locally. I do want to see the valves and head before it is re-assembled. The dealer also said they would clean all the parts internally before re-assembly. I am sure it will run better.