Engine shakes

KALAN

MEMBER
2004 CADILLAC SRX
6 CYL
AWD
AUTOMATIC
67,000 MILES

Hi.I have cadillac srx '04.A week ago my engine light goes on. Then after few days start flashing and my engine start shaking. Then sometimes light goes off, then again on and steady, then again flashing and engine shaking.I changed spark plugs but that not solved my problem. What to do?Maybe I have misfire cylinder. How to check that?

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,747 POSTS

When the light is flashing, that usually indicates a misfire. When the light is on, you need to have the computer scanned. It will identify which cylender is misfiring. From that point, recheck the plug to make sure it is properly gapped and not fouled. Also, the coil pack for that cylender should be checked.

Let me know what youf ind.

Joe

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Monday, December 20th, 2010 AT 10:23 PM

KALAN

MEMBER
3 POSTS

Ok. After scanning here is the codes:po205/injector circuit/open-cylinder 5; po300/random-multiple misfire detected and po305 cylinder 5 misfire detected. Po300 is because maybe before scanning I removed one by one each coil pack and find that cylinder 5 is not reacting (not working)I thought it's coil pack, I bought new but I returned because it was the same. Mechanic check and he said that coil pacs are good. He thought first maybe injector from cylinder no:5 or o2sensors(he find that two o2 sensors not working ok, they not changing their numbers they working flat. He checked injector and he found that is ok. Now he saying 90% he is sure that ECM is not good. There is no ground on cylinder no:5 and that's why he is not working properly. Ecm cost $400 new +$80 programming. What do you think?Go to the dealer or buy some used ECM or ask for another opinion?Is possible that ECM causing the problem with cylinder 5. If Ecm is not good why is not same for all cylinders?

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Thursday, December 30th, 2010 AT 3:44 AM

FACTORYJACK

MECHANIC
4,159 POSTS

An ECM is possible, they usually employ separate ground drivers for each injector. It would be premature to suspect the ECM, without checking first that the circuits involved have good integrity. A simple continuity check of the ground circuit from #5 injector to the ECM might reveal a problem. Coincidentally, was the two 'bad' O2 sensors and the same bank that #5 cylinder is? Without fuel, that cylinder is basically an air pump, and that extra air makes an oxygen sensor read differently, and they are not necessarily faulty, just doing their job.

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Thursday, January 27th, 2011 AT 3:36 AM

KALAN

MEMBER
3 POSTS

It was ECM. It was still under warranty but they found something else first to change but that did not work and found ecm?

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Saturday, February 5th, 2011 AT 4:12 AM

JACOBANDNICKOLAS

MECHANIC
109,747 POSTS

First, I'm glad you got it fixed. However, the part they replaced that wasn't needed, I would be upset about. Did they offer you the old part (that was still good) back? If not, I would tell them since they made the mistake, they should cover the part. Where I live, we have to offer the old parts back to the customer.