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Rough Idle and low vacuum after timing belt change

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littledog

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Discussion starter · #1 ·
Hey guys, need a little help here.

After the timing belt change, my idle is rough and it's like "booooo-pause-pause-booooo booooooo" and if you look at the engine the whole engine shakes a lot during the "pause" periods. The idle is nowhere near low as it's in perfect 700-750rpm range. I've read it might due to ECU being resetted but it's been six days now and it's still doing the same thing. Also the vacuum reading is 16 in Hg comparing to solid 20 inHg before the t-belt change. And one more thing I notice is if I tap the acclerator slightly, the vacuum raises to 20 in Hg then start to drop llike normal.

Any ideas on what's wrong? Thanks.
 
#10 ·
That sucks, seems like they are trying to avoid fixing it...
Go back and get them to allign the timing marks infront of you. If the timing marks don't look like this they didn't put it on right.

Image


The ecu dosn't control vacuum either. It should be at 20 in hg like before.

Print that picture (or the entire vfaq) and show it to them.
 
Discussion starter · #11 ·
They showed me the marks and they are right on just like the picture you posted. The techs told me when they remove the old timing belt the marks were not aligned from the factory and now they aligned it according to the manual and now I have this problem.

Any ideas on why?
 
#12 ·
It's obvious the problem started after the timing belt change, so they are the ones who should be investigating, not you. If it was me, I would not only make sure the cam gear timing marks line up, but also the crank and oil pump. The gears uptop may look like they are pointing at each other, but the crank and oil pump may be waaay off. And the only way to see if they are lined up is to remove the lower timing belt cover, which I doubt they did to show you the timing was 'on'. If they fubared the timing job, I'm betting they also fubared the oil pump/rear balance shaft timing. That gear may look like it's pointing at the timing mark, but it can be out of phase since the it also spings the rear balance shaft. I would just print out the VFAQ on timing belt jobs, slap it in their faces and show them the highlighted red sections. Shops like this piss me off because I had a similar problem and they f*cked up my oil pump sprocket timing, saying it was "all lined up", but later leading to balance shaft failure. I had to learn how to do the timing job myself to correct their $400 f*ck-up.

Cam gear marks should be pointing at each other with the dowel pins at 12 oclock

Oil pump sprocket needs to point at it's timing mark and it should fall counter clockwise if the timing mark on the oil pump sprocket were pointed straight up at 12 oclock. If it falls clockwise, rotate it a compete 360° and test again.

An ECU wouldn't go suddenly bad after a timing belt change. Nor does the ECU need to 'relearn' an idle.


my_gst95
 
#13 ·
my_gsT95 said:
Nor does the ECU need to 'relearn' an idle.
Click to expand...
That all depends on where the BISS is adjusted to. When the ECU is reset, it defaults to a specific learned idle adjust value. If the way your BISS is adjusted usually has this value way off, then the ECU has to relearn the value associated with your BISS adjustment. This takes a while. Depending on how often the car is driven, it could take a week. It could take an hour.
 
#14 · (Edited)
"They showed me the marks and they are right on just like the picture you posted. The techs told me when they remove the old timing belt the marks were not aligned from the factory and now they aligned it according to the manual and now I have this problem.

Any ideas on why?"

If it's off by a tooth it's hard to see. You can get the cam gears lined up and it looks fine but it's not. The problem is that you can't get down to head height to make sure the cam gears align with eachother and with the top of the head because the fender blocks the direct view. If you use a mirror you can get a direct look at the 2 marks and the head at head hieght to see if it's aligned right. This is the method I use... just make sure you get the view to be directly at head height.

Or get them aligned then use a straight edge to make sure all 4 cam gear markings are along the straight edge.

I've had to go bitch out a Mitsu dealer for doing this wrong to a friends car... it happens all the time.

The ECU will not take weeks to restore proper idle.
 
#15 ·
Sorry to jack the thread, but I'm having a very similar problem. Idle is wierd, sounds like I have cams, and when I blip the throttle lightly the rpm instead of jumping up would bog and the car would shake, then it would go up slightly. Also vaccum reading is off.

When black boost said "Your turbo should be also very laggy." I was like HOLY MOLY. Because my 50 trim isn't hitting full boost (set it at 15psi for now) until 5000rpm.

But here's the thing..... I did not recently have a timing belt change nor messed with the cams. So could I have a different problem or could some weird reason it jumped a tooth and now i'm off timing?
 
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Discussion starter · #16 ·
Thanks for the help guys.
I am pretty sure the balance shaft is aligned properly since it didn't before and I had them to do it correctly according to the vfaq. The techs read the vfaq already and all the marks including the lower ones appears to be like where it should be.

Quadcylia, I don't quite get what you are talking about. I am confused the human head or the engine head :confused:
And there are 4 cam gear marks?! Isn't there just two?
 
#17 ·
In the post with the timing marking pics above look at the pic in the top right. It shows the cylinder head height. That's very important because the cams gears must not only align with eachother but they must also align with the top of the cylinder head when aligned or else the timing is off.

Now you can't get a direct view of the timing marks from the cylinder head height to see if all are aligned with the engine in the car because the fender blocks the view. You are actually looking down a bit at the marks and the top of the cylinder head. So if the timing is off by a tooth and the gear markings align just on the high side of the top of the cylinder head then from the angle you are checking from things will actually look great. But if you were to get a direct view from the same height as the top of the head you'd be able to see that the timing markings when aligned with eachother are actually just above the top of the cylinder head. The way I do this is to use a mirror placed at the height of the top of the cylinder head just inside the engine bay to reflect up to my eye. That way I can get a proper direct view.

I hope you can understand what I am saying... it's hard I guess to put in words.

This may or may not be your problem but I've seen it a few times with similar symptoms.
 
#19 ·
I had same problem, not T-Belt

Yo, I had the same problem. I ripped the timing apart over and over thinkoing it was off a tooth, each time it wasnt. In fact, I dont know why but before the T-belt chage the car ran great but as soon as i put the new one on there, it ran like poop. I did everything I could, so I finally tested the MAS Sensor on the computer, my baro meter was shot. I replaced it and vacuum returned to normal and no more stumbling. Also my o2 sensor was bad too. Long shot but its worth a shot atleast to find out if thats the problem.
 
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