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I;ve been working on a “97 thunderbird. It’s been running rough, and smelling like it burns a little bit of oil. It never threw any codes at me till last week. It gave me P1151 HO2S detects lean. I have ruled out EGR problems, fuel pressure, Mass air flow, and didn’t find any leaks with the torch. I decided to do a compression test to see if it was worth throwing parts at to try to solve this very non-discript code.
The compression test came back with all 8 cylinders fairly close, but MUCH lower than what I anticipated. (59-69 psi.) I haven’t been able to come up with the compression ratio of this engine, but those numbers seem lower than what I would expect. Does anyone happen to know what those romeo 4.6L SOHC engines should test at?
Also, when pulling the plugs I noticed a little bit of carbon on all, but a few of them had ash deposits on them (and they’re not very old). This brings up the question of what is the likelyhood that a valve problem is causing the ash, low compression, and burning oil? How about a lean code? Could a valve problem cause the engine to throw a lean code? how about an intermittent miss?
I thought I would ask these questions before just slapping parts on. I recently watched my brother spend 3 grand on someone else to throw parts at a “bank 2 detects lean code.” And, the problem still isn’t resolved. Could valves be his problem too?
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I put on a new intake plenum gasket. Notice I said put on instead of replaced. the intake manifold has a orange rubber flange around the input hole where the throttle body assembly bolts on. When I saw that, I thought this would be the problem for sure. But, much to my dismay, it’s still running quite rough.
I have to go to work soon, and I will recheck for leaks. I once had a mustang that the ignition timing was off, and it kinda’ felt similar to how this car is running. This car uses the computer to control ignition timing, but could the mechanical timing cause similar problems?
Is there a way to check my cam timing without taking it apart? Also, Is there a way to check my valves? Where should I go from here?
Driving around at work this evening it hit me what a few of you guys might have been touching on. HEAD GASKET. let me run this by you guys and see what you think. My coolant is dark green, and has kind of a swampy film on top in the overflow tank. I have blue / white smoke out of the exhaust pipe that smells sweet. And previously when I noticed it running rough I pulled the plugs and noticed a liquid on one of the plugs. ( I thought it was oil at the time. Now I’m not sure.) I have also been chasing down a cooling issue. It runs pretty hot, (temp 2/3 rds of the way up) then my fan will kick on and it goes down to halfway. It runs rough, and seems to be missing power from what I know about ford V8 cars.
On the other hand: I don’t see coolant in the oil or visa versa. Also, I don’t seem to be losing coolant.
Could this be the problem? How do I do a hydrocarbon test if my radiator doesn’t have a cap?
Quoted From stormchicken:
Driving around at work this evening it hit me what a few of you guys might have been touching on. HEAD GASKET. let me run this by you guys and see what you think. My coolant is dark green, and has kind of a swampy film on top in the overflow tank. I have blue / white smoke out of the exhaust pipe that smells sweet. And previously when I noticed it running rough I pulled the plugs and noticed a liquid on one of the plugs. ( I thought it was oil at the time. Now I’m not sure.) I have also been chasing down a cooling issue. It runs pretty hot, (temp 2/3 rds of the way up) then my fan will kick on and it goes down to halfway. It runs rough, and seems to be missing power from what I know about ford V8 cars.
On the other hand: I don’t see coolant in the oil or visa versa. Also, I don’t seem to be losing coolant.
Could this be the problem? How do I do a hydrocarbon test if my radiator doesn’t have a cap?
yep i had asked about the water usage incase of a head gasket problem. you just use your over flow tank for a rad cap. it works the same.
Again, I would check for vacuum in the crankcase.
Also, being an obd2 vehicle gives you the advantage of being able to scan and the fuel trim numbers would be of immense help in diagnosing this problem.Here is the rundown on doing checks for coolant leaks and head gasket leaks however I would make sure you eliminate other the possible causes first.
http://www.youtube.com/watch?v=hUzOTnsWImII ran a hydrocarbon test this afternoon. I had a couple of hours in between school and work. The fluid stayed blue. I was hoping to get it while it was smoking, but naturally it didn’t smoke. Ran that sucker for an hour and it didn’t smoke. HMMM… Also, in the process I noticed that my cooling problem wasn’t happening. So that has to be the cap. It wasn’t all in vain, and it only cost me $8 and some time. I should have some time this weekend to run the leak down this weekend. Please keep checking this thread.
I’ll be honest though, I’m still not convinced that it’s not a vacuum leak somewhere. Is there a sure fire way to check for leaks. What about my PCV valve? is there a way to test it? (It’s only a few months old but still.)
It’s not likely the new part is bad and if there isn’t a problem now just ride it out for a while and see what happens, you don’t need to go down the road of throwing parts at something in hopes it will do the trick, that gets expensive and is often ineffective.
Quoted From stormchicken:
Had to go out of town for a while for family matters. I think I got this problem solved. I checked the wiring harness on the O2 sensor. it had a bad connection in the connector on the car side. Rigged that and BAM!!! Idle smoothed out. Seems like it gained some power too.Thank you EVERYBODY for your help! I greatly appreciate it.
connections connections connections lol they will get ya. well glade you found it and thanks for the update.
Had to go out of town for a while for family matters. I think I got this problem solved. I checked the wiring harness on the O2 sensor. it had a bad connection in the connector on the car side. Rigged that and BAM!!! Idle smoothed out. Seems like it gained some power too.
Thank you EVERYBODY for your help! I greatly appreciate it.
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