07 aveo hatchback running terrible after timing belt service - HELP!

I just had my 07 hatchback in for a bunch of work and had the timing belt, water pump and idler replaced along with a further host of issues - front struts & mounts, outer tie rods, stabilizer bar links & bushings, both CV axels & replacing the failing AC compressor.

previous to the service the car would idle rough - but ONLY with the AC on, accompany'ed by a grinding sound. With the AC off it would idle normally. I had the compressor verified bad by two different mechanics.

post service - the car now idles very rough, surging between 700 and 900 rpm at idle. it did NOT do this before the timing belt service. there is also a small vibration through the steering wheel at highway speeds (on fresh brand new blacktop no less).

the original AC compressor i supplied to the shop who did the work was diagnosed as defective, causing the car to run under strain. the unit was replaced with one provided by the shop through their parts supplier.

the shop told me that its possible that its a fuel management issue that will resolve itself after a day or so of driving. I suspect that the timing belt is off by a tooth & that the AC compressor i provided was actually good.

is there any way to diagnose this as being out of time so that i can address the issue properly with the shop that did the work?

if the timing IS off by just a little bit, is my engine at risk? or just going to run like crap?

any help is appreciated

The idle problem could be caused by a number of things, and it's not at all certain it was caused by the work the shop did (because it was happening beforehand as well). Some of the common culprits are vacuum leak, IAC or the throttle body itself. But there are others as well. The only sure way to verify the timing is to open it up and check the marks. Even a bad compression or leak down test result doesn't prove it's the belt, because it's possible something else is causing the low compression. Unless it's running badly beyond idle, IMO it doesn't sound like timing is the problem. And even though It also doesn't sound like spark plugs are the problem, when were they changed last?

this sounds similar to my issue with my 04. it was out of time by 1 tooth and it ran like this accompanied by bad MPG

spark plugs & wires were serviced on 6/21 - 8500 miles ago
fuel system cleaning was performed on 7/12 - 6500 miles ago
tires were balanced/rotated 400 miles ago and have a total of 5900 miles on them since they were installed new, i have pirelli p4's on there so they're not a sh!t tire.

i never said anything about low compressION - i said the AC compressor was replaced because it was failing. when i would turn on the AC the strain on the motor (from the failing AC compressor) would cause the car to idle rough - but this was the ONLY time the rough idle symptom showed itself before the service. turn the AC off and rough idle would go away immediately - along with the grinding noises from the AC compressor. the rough idle is constant now - AC on or not.

there is vibration at highway speeds that i can feel through the steering wheel thats constant - even on freshly laid blacktop... i hit a freshly resurfaced section of i-96 outside of novi to test and make sure it wasnt something coming up through the steering & suspension system.

Quote:

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Originally Posted by plant.one

... i never said anything about low compressION ....

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I mentioned low compression only because you asked about how to determine if the timing is off.
So once again; if it was off, that would show up in a compression or leak down test. But OTOH a bad test also wouldn't be positive proof that the timing is off. Only checking the timing marks can answer that question.

so the service engine light went off today - code p0300 - cylinder misfire - random cylinders

the gas mileage is in the toilet, under 20mpg when i topped off the tank today (94 miles 5.3 gallons) compared to its usual 30+ highway.

dropped it back off at the mechanic this evening, lets see what they find

what a giant pain in my ass.

If the belt was replaced and not broken, then it is most likely off one tooth, it is easy to make that mistake, and explains all your symptoms. The only other thing it could really be, is if a position sensor, or something was not plugged back in on reassembly not sure what all they would have torn apart. but the sensors would have a CEL.

I for one agree its probably off a tooth.

it probably is off a little. EXACT symptoms as mine had. bad idle and bad mpg. bet money it's off time!

got her back yesterday afternoon, purring like a kitten.

timing belt was positioned correctly.

they went into the computer, cleared out the codes and essentially reset it to factory defaults.

they think one of the censors may have faulted when they ran the battery down - he said they left the door open when it was up on the lift the other day while it was in there.

that might explain the air bag light too.


either that or somebody forgot to plug a sensor back in all the way when they put my car back together:dontknow: . it is kinda how my van acted when the cam position sensor was failing on it - although in that case the SES code pointed directly to it.

either way happy outcome, my car is running smooth again.

I guess I lost my money! lol. at least it's fixed. thanks for responding with the fix!