Rough idle, misfire, low compression

CLAYTONWHITE49

MEMBER
2006 CADILLAC CTS
2.8L
6 CYL
2WD
AUTOMATIC
147,000 MILES

Rough idle no compression in number one cylinder. Misfire one, three, and five. Next check misfire in one, three, four and six. Then misfire one. Loss transmission with computer several times. Compression check 1- 30.3-95, 5-94.2, 4 and 6 good ( less than 10 psi loss) leak-down test next. Bought car from auction. Have to bypass anti-thief to start (turn key on jumper wire in fuse box under the hood). Changed coil on one and three. No fire in one. Then got fire. No compression. Did not do anything, but I have fire in one. But number one would lose fire at certain times.

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,895 POSTS

Hello,

Can I ask you how you bypassed the alarm? No one can tell me how to do it?

It sounds like you have a camshaft actuator/timing chain issue with the engine which is common. Below are diagrams on how to do the job.

You will need to pull the balancer here is a guide:

https://www.2carpros.com/articles/how-a-harmonic-balancer-works

Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken

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Sunday, January 7th, 2018 AT 8:14 PM

CLAYTONWHITE49

MEMBER
3 POSTS

Okay, in the fuse box under the hood of my car is a I believe a black and yellow wire. You touch that wire and just put it on anything to ground and the starter will turn over. But you must have the key on for it to start. But the last time I did it it would not work. So I took the battery post off and tried it, no good. Then the fan inside the would come on full blast. Turned the fan off post off then back on. There goes the fan again. Post off then on turn the key use the jumper wire then it would start. The car is possessed or the computer is fried. I do not know. I am going to do a leak down test today and if that is good I am going to see if the injectors are getting fire then the brain box. Then who knows?

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Sunday, January 7th, 2018 AT 9:47 PM

KEN L

MASTER CERTIFIED MECHANIC
42,895 POSTS

It sounds like a BCM issue which contains the security system. I would have the BCM codes run to confirm the issue. If you need it replaced a shop will need to program it for you. Below is the location.

Check out the diagrams (below).

Please let us know what happens.

Cheers, Ken

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Monday, January 8th, 2018 AT 11:49 AM

CLAYTONWHITE49

MEMBER
3 POSTS

I did a leak down test on my number one and I have air coming out of my number three and a little out of the number five on the number three air comes out the number one and five. So my head gasket is leaking between the cylinders. On two, four and six sounds like a little air is coming out of my oil fill. So I guess it would be better to just get engine instead of a head job since I do not know if it is cracked or warped.

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Monday, January 8th, 2018 AT 1:25 PM

KEN L

MASTER CERTIFIED MECHANIC
42,895 POSTS

Yep sometimes its best to swap the engine out instead of trying to fix an engine that has been abused or overheated.

Please let us know what happens.

Cheers, Ken