Need help trouble shooting?

[BigDaddyCee]

Hi Guys,
I know you don't ever see me in this forum but I was wondering if I could get some help with my daily driver? I have a 93 2.3 litre coupe, automatic tranny all stock. Recently I have expeienced intermitent power problems! My muffler blew-up on friday and I had to drive/limp it home. It was very weird It would lag and cough and spit and not produce any power especially from a dead stop. Not to mention how noisy it was(sounded like a sherman tank). Worst thing was all the long leering looks from other drivers. I also had let it warm-up about fifteen mminutes before driving that day. I also stopped one time to have a look underneath and noticed that the cat closest to the exhaust manifold was glowing red?. So the next tay I took it to the muffler shop It didn't start acting up until I got close to the mufler shop (about 10 k)and talked to the guy and told him all this. He said that the engine was running really rich that was why the cat was red hot, it was burning off all the excess fuel? Any way he looked and we agreed that the muffler was shot so he replaced it. Then the car ran fine all that day Saturday. Then on sunday I drove it alot and it was pretty good it only lagged and lost power one time for about a half of a kilometre? Do I have something like a sensor going south on me? My check engine light is not on? Please help?

 

[RustBucket]

Well if the check engine light is not on, then the computer isn't seeing anything outside of its normal ranges. What I'd do in this case is look at things that the computer has no oversight on. I've seen bad plug wires cause this,as well as fuel system issues (bad regulator, leaking or stuck injector) A bad coolant temp sensor will cause a rich condition, but I don't know if it would be bad enough to cause the problems you're seeing.

The easiest thing to do would be to check the regulator. Pull the vacuum line and see if the line smells like gas.

Pull the passenger side spark plugs and check them for color. This will tell you if it's common across all cylinders or isolated to just one. If it's just one cylinder with a black spark plug, I'd suspect a bad injector.

Test the plug wires by waiting until dark and checking under the hood for arcing between the wires and a nearby point or another wire. On the intake side, don't rule out wires arcing against the aluminum. I chased my tail for a few hours on my kid's 2.8 Chevy because the coil wire was arcing against the back of the upper intake manifold. Same deal, rich as hell, blew up the muffler (scared the livin you-know-what out of me), would barely run. OH yeah, don't reach for the wire to pull it away from whatever its arcing against while the motor is running

Keep us posted as to what you find and we'll help all we can.

 

[BigDaddyCee]

Thanks RustBucket,
This sounds like a good place to start. The only things I didn't include in my first post is that the oxygen sensor was replaced about a year and a half ago aswell as a tune-up that included new spark plugs and wires, fuel filter and I have 234,000 kilometers on the engine. Also the muffler guy did a back pressure test too and it came out at 3 lbs which he said was good. I will post back my findings later.

 

[BigDaddyCee]

O.K. I pulled the vacuum line off the fuel regulator and it doesn't smell like gas. Also pulled the pass side spark plugs and they are in almost perfect condition definately not black very slight gray deposits? I will check the plug wires later.

 

[vristang]

The EEC-IV can throw trouble codes but never trigger the CEL. You need to pull the codes and see what the computer thinks the problem could be.

Plugs will show the condition of the mixture just before the motor was shut down. So if it was running well when you pulled into the driveway, that is what you are seeing on the plugs now.

I am guessing that the back pressure test was to ensure that the cat hadn't plugged? Did he run pressure through the exhaust from the exh valve? I am curious about the process.

Rustbucket gave some good things to check, but I would start with the codes.
Good luck
jason

 

[RustBucket]

You'd think with it running that rich it would blacken the plugs.

According to your original post, it only acts up after it's been running for awhile. Could this be happening as soon as the motor comes up to temp? What I'm thinking is that the coolant temp sensor may be bad. If it keeps reporting low temps back to the ECU, it'll keep dumping fuel thinking the motor is cold. The coils and ignition module would throw a code and you stated that the plugs and wires are fairly new, the fuel pressure regulator checks out ok and the plugs aren't sooted up, sooo I'm trying to come up with everything that might make it run rich. Keep plugging at it and I'll help as much as I can.

 

[RustBucket]

Good point on the ECU. I hadn't thought about that. You're right about the plugs too. Which makes me think that it's only happening under certain conditions.

 

[BigDaddyCee]

O.K. I am going to pull the codes as we speak. I will post my findings shortly. The back pressure test was taken at the union after the cats and before the muffler. Yes the test is to see if the cats have melted down. I could only view from the waiting area but it was some type of meter that was hooked up to the battery then they started the engine and revved it once to get their reading then shut it down.

 

[BigDaddyCee]

O.K. looks like code 118 came up the first time I pulled the codes. Then the second time i got the all clear 111 code and the continuous codes 223&224 which have come up in the past. The first time I let it warm up and ran it around the block before taking the codes. The second time was sitting in the drive way without any driving in between. Codes were koeo and 118 says that the "engine coolant temperature sensor above maximum voltage/0 to -40degrees indicated" Temperature guage inside said coolant temp was 120-140 degrees f. Do I need a new coolant sensor? I will drive it around again and take the codes one more time.

 

[RustBucket]

Yup, replace that sucker. If the computer is interpreting the signal from the CTS as 0 - -40 degrees, then its never coming off of cold start enrichment. Kinda like driving with the choke stuck on a carburetor.


Hehe we don't need no stinkin' computer. We were heading for the CTS anyway. Might have saved a little time though. Oh well. We all learned something today...didn't we?

Now comes the fun part: getting that sucker out of the tee fitting. Over where the heater hoses come out of the firewall you'll see the tee. It's on one of the hoses. Best thing to do is take the tee out of the line. put the fitting in a vise and remove the sensor that way. I've found it's damn near impossible to take it out while it's on the car (unless it's been replaced before).

 

[BigDaddyCee]

Thanks,

You guys are great, The extra help is much appreciated, I have already swapped it out. And Yes I had to do it the way you recommended In a vice, it was stuck good in the tee. I will monitor it and do a final post in the next day or two.

Thanks again

Brian

P.S. I know where I'm coming for help the next time she starts acting up.

 

[RustBucket]

Yet another Brian!

Glad we could help. I hope we're this good next time


Happy Motoring.

Brian

 

[BigDaddyCee]

Update

O.K. Guys thought that I would post whats happened over the last week. Well, alot, So I repaced the coolant temp. sensor and that helped for awhile. Then the same problem. Severe lack of power and fuel dumping into the cats causing them to glow red/orange. So as suggested earlier I checked out the fuel pressure regulator again. Took it off and had a look then an oilish substance started coming out of it, quite a bit probably full. So I knew this wasn't supposed to be like this so I changed that. Thought this was the problem. No not yet(although this did seem to fix my hard to start in cold weather problem that has been nagging me). So then I thought maybe the thermostat was stuck open so I changed that. No not the problem yet. Meanwhile I have been checking the codes and they have been coming up with a pass. So I go to the wrecker and get the coil packs off a 91 stang aswell as the ICM. Changed the coil packs because it was an old continuous code problem still not fixed. This didn't help. So I start scanning through my chilton manual and come across a section that says codes 213/412 or " no codes "and lack of power-spout open or low. Says to replace icm(ignition control module). So I did and have been driving it since Tuesday and it is like a whole different car. Runs like a top! In this particular case a code reader didn't help much? Had to throw parts at it until I could find the right one. Thanks again guys. I was just about ready to dump her in the bay!