Scary engine noises and horribly running. Need ideas.
07-11-2021, 06:33 PM
#1
Thread Starter
Scary engine noises and horribly running. Need ideas.
I had a cooling fan relay issue a year or two ago. It did overheat once and got quite hot couple of other times. Then, I was getting a bit of a coolant smell on occasion when I started the car in the garage, (smell more concentrated in there). I put UV dye in the coolant to see if I could find any leaks, but no. I tested compression and got crazy good and consistent compression. I scoped the cylinders (twice) to look for issues. I saw what MAY have been coolant on a piston top.
I then had dark smoke with no oil smell, and it was overall running rich. That eventually went away as well. So with all of that info, I thought that the overheating very well may have cause a head gasket problem and was planning to address. For a while, I've been struggling with a lumpy idle and rarely, the car dying at low idle. Just not wanting to idle correctly.
And about two weeks ago, I drive it for about five minutes to run to a store and pulling in to the parking lot, it started running horribly. Bucking, rattling, sounded like perhaps two cylinders were missing. And then what sounded like backfiring with a metallic pinging sound with each bang, though the bangs were muffled. Scary sounds. So, I immediately drive it back home. It runs smoothly above 3800 RPMs, but horrible again at anything less. So I can't think it's rods, bearings or retainers or anything like that.
I scope the cylinders again and #4 looks pretty black and the plug from that cylinder was much more degraded than the others. So I start thinking about what all may be the problem. It's closing in on 150k miles, with a lot of things still factory installed, so I decide to swap out some of the consumable items in the car. General freshening. I swap the injectors (assuming the rich running and black cylinder and plug is indicative of injector issues). And swapped the original coil packs for new ones. And a new MAP sensor. and new plugs, gapped perfectly. And go to start it and the exact same thing happens. Still.
SO now I assume that the overheating did damage. To what extent I don't know. And I looked at the valve train and scoped all the cylinders and didn't see anything scary internally. But the super rough running is just too much for me to figure out at this point.
Any ideas are welcomed.
I then had dark smoke with no oil smell, and it was overall running rich. That eventually went away as well. So with all of that info, I thought that the overheating very well may have cause a head gasket problem and was planning to address. For a while, I've been struggling with a lumpy idle and rarely, the car dying at low idle. Just not wanting to idle correctly.
And about two weeks ago, I drive it for about five minutes to run to a store and pulling in to the parking lot, it started running horribly. Bucking, rattling, sounded like perhaps two cylinders were missing. And then what sounded like backfiring with a metallic pinging sound with each bang, though the bangs were muffled. Scary sounds. So, I immediately drive it back home. It runs smoothly above 3800 RPMs, but horrible again at anything less. So I can't think it's rods, bearings or retainers or anything like that.
I scope the cylinders again and #4 looks pretty black and the plug from that cylinder was much more degraded than the others. So I start thinking about what all may be the problem. It's closing in on 150k miles, with a lot of things still factory installed, so I decide to swap out some of the consumable items in the car. General freshening. I swap the injectors (assuming the rich running and black cylinder and plug is indicative of injector issues). And swapped the original coil packs for new ones. And a new MAP sensor. and new plugs, gapped perfectly. And go to start it and the exact same thing happens. Still.
SO now I assume that the overheating did damage. To what extent I don't know. And I looked at the valve train and scoped all the cylinders and didn't see anything scary internally. But the super rough running is just too much for me to figure out at this point.
Any ideas are welcomed.
07-12-2021, 02:56 AM
#2
No tears in your intake tube? Vacuum leak somewhere? Idle issues are usually the idle air control valve. @Soviet has a DIY video that shows how to clean it.
Only cylinder 4 plug is fouled?
Also you said you looked at the valvetrain, did you check the valve clearance? Its free preventative maintenance, tight valves will burn themselves and the stuff they interact with.
Only cylinder 4 plug is fouled?
Also you said you looked at the valvetrain, did you check the valve clearance? Its free preventative maintenance, tight valves will burn themselves and the stuff they interact with.
07-12-2021, 06:21 AM
#3
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Push 100psi of air into each cylinder at TDC (like a leakdown test).
Open the radiator cap and see if the coolant is expanding. If compression air is leaking into the HG, this is a pretty solid way to confirm. I just did a head gasket and this method is what I used to confirm mine was blown.
I also used it to confirm a good seal when I was done.
You said your compression test turned out "good". What numbers did you see?
Open the radiator cap and see if the coolant is expanding. If compression air is leaking into the HG, this is a pretty solid way to confirm. I just did a head gasket and this method is what I used to confirm mine was blown.
I also used it to confirm a good seal when I was done.
You said your compression test turned out "good". What numbers did you see?
07-12-2021, 07:14 AM
#4
Thread Starter
Thanks for the responses. Slowcrash_101. It's an '06, so no IAC. And it was kind of an idle issue, but now, horrible.
I didn't check the valves, as I adjusted them about nine months ago and it isn't driven a lot. And yes, #4 was the one that was really fouled.
I didn't check the valves, as I adjusted them about nine months ago and it isn't driven a lot. And yes, #4 was the one that was really fouled.
07-12-2021, 08:08 AM
#5
Sounds like you checked compression a while back but not since you've had the new issues. Check compression. Get a spark tester and actually check for spark at each coil. Check your fuel pressure. Quick check can be removing the vacuum line from the fuel pressure regulator and see if your symptoms improve. Check all your vacuum lines.
Edit: you mention replacing several parts. Did you go with OE parts, particularly the MAP sensor?
Edit: you mention replacing several parts. Did you go with OE parts, particularly the MAP sensor?
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Edbun (07-12-2021)
07-12-2021, 09:55 AM
#6
I had a cooling fan relay issue a year or two ago. It did overheat once and got quite hot couple of other times. Then, I was getting a bit of a coolant smell on occasion when I started the car in the garage, (smell more concentrated in there). I put UV dye in the coolant to see if I could find any leaks, but no. I tested compression and got crazy good and consistent compression. I scoped the cylinders (twice) to look for issues. I saw what MAY have been coolant on a piston top.
I then had dark smoke with no oil smell, and it was overall running rich. That eventually went away as well. So with all of that info, I thought that the overheating very well may have cause a head gasket problem and was planning to address. For a while, I've been struggling with a lumpy idle and rarely, the car dying at low idle. Just not wanting to idle correctly.
And about two weeks ago, I drive it for about five minutes to run to a store and pulling in to the parking lot, it started running horribly. Bucking, rattling, sounded like perhaps two cylinders were missing. And then what sounded like backfiring with a metallic pinging sound with each bang, though the bangs were muffled. Scary sounds. So, I immediately drive it back home. It runs smoothly above 3800 RPMs, but horrible again at anything less. So I can't think it's rods, bearings or retainers or anything like that.
I scope the cylinders again and #4 looks pretty black and the plug from that cylinder was much more degraded than the others. So I start thinking about what all may be the problem. It's closing in on 150k miles, with a lot of things still factory installed, so I decide to swap out some of the consumable items in the car. General freshening. I swap the injectors (assuming the rich running and black cylinder and plug is indicative of injector issues). And swapped the original coil packs for new ones. And a new MAP sensor. and new plugs, gapped perfectly. And go to start it and the exact same thing happens. Still.
SO now I assume that the overheating did damage. To what extent I don't know. And I looked at the valve train and scoped all the cylinders and didn't see anything scary internally. But the super rough running is just too much for me to figure out at this point.
Any ideas are welcomed.
I then had dark smoke with no oil smell, and it was overall running rich. That eventually went away as well. So with all of that info, I thought that the overheating very well may have cause a head gasket problem and was planning to address. For a while, I've been struggling with a lumpy idle and rarely, the car dying at low idle. Just not wanting to idle correctly.
And about two weeks ago, I drive it for about five minutes to run to a store and pulling in to the parking lot, it started running horribly. Bucking, rattling, sounded like perhaps two cylinders were missing. And then what sounded like backfiring with a metallic pinging sound with each bang, though the bangs were muffled. Scary sounds. So, I immediately drive it back home. It runs smoothly above 3800 RPMs, but horrible again at anything less. So I can't think it's rods, bearings or retainers or anything like that.
I scope the cylinders again and #4 looks pretty black and the plug from that cylinder was much more degraded than the others. So I start thinking about what all may be the problem. It's closing in on 150k miles, with a lot of things still factory installed, so I decide to swap out some of the consumable items in the car. General freshening. I swap the injectors (assuming the rich running and black cylinder and plug is indicative of injector issues). And swapped the original coil packs for new ones. And a new MAP sensor. and new plugs, gapped perfectly. And go to start it and the exact same thing happens. Still.
SO now I assume that the overheating did damage. To what extent I don't know. And I looked at the valve train and scoped all the cylinders and didn't see anything scary internally. But the super rough running is just too much for me to figure out at this point.
Any ideas are welcomed.
07-13-2021, 07:25 PM
#7
Thread Starter
The map sensor is a Standard Motor Products one part # AS336. Compression was 176, 174, 170, 173 in December. I will test again. As far as vacuum leaks, where is a vacuum system diagram? My service manual doesn't seem to have one. I am tempted to try the old trick of streaming propane around the hoses while it's running to see if it changes things. No oil in coolant or coolant in oil. And the '06 fuel pressure regulator is in the tank.
Could a head gasket issue really cause this?
Could a head gasket issue really cause this?
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07-14-2021, 03:13 AM
#8
A bad pedal position sensor can cause garbage idle and the car stuttering at lower speeds, it sometimes won't even throw a CEL.This issue is common on DBW cars. Wouldn't explain the plug fouling though.
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Edbun (07-14-2021)
07-23-2021, 04:19 PM
#9
Seems like a candidate for a leak down test to me.
08-05-2021, 12:31 PM
#10
Thread Starter
Solved
Ok, I knew that I wasn't going to be able to find whatever it was, so I took it to the top expert in my state. Took quite a while, but eventually, through a process of elimination, it turned out to be two things. The ecu was bad AND the injectors I was sold are wrong for the car. They changed both and now it runs fine. Lost my tune, but it works perfectly. No engine damage, no head gasket issues, just the computer and the injectors. Thank you all much for the support and suggestions.