Problems after cambelt change

[Harold]

Hello chaps,

Just returned from having cambelt, hydraulic tensioner, idlers, alt/ac belts and water pump changed and my car isn't healthy at all!

The problem is that when I put my foot down, I can hear the turbo spooling and showing plenty of boost on the gauge but the car doesn't go any faster. And I'm convinced there is a slight rattle from the engine when revved, as though something is loose.

Can anyone suggest a cause for this problem please?
The car is going back to the garage on Monday but I'd like a few ideas first. I could have done without this.

Thanks.

[Nick86]

checked ignition timing?

[Harold]

I don't possess a timing light so that will have to wait until it goes back to the garage. Would wrong timing cause this problem?

[raptor95GTS]

if the cambelt has been changed I'd be putting money on the mechanical timing being incorrect which then means the dizzy has to be moved way out to get the static timing back. If the garage is looking at it Monday they should be able to confirm this. The pro's on here can explain how to check the mechanical timing

[Harold]

Ok, will have them check, The car did seem to run badly also. Is this the right thing I need to look at - http://mr2.noegruts.com/ignition/timing.htm

Can any damage occur from driving with incorrect timing?

[Quigonjay]

could be as simple as an intercooler pipe popped off

[paul port]

You cannot correct Mechanical timing by rotating the distributor (Ignition timing)

Mechanical timing (Cams Vs Crank) is fixed by the cam-belt, and would be out if the cams were not correctly positioned when the new belt went on.

There are markers on the cam pulleys, Belt, and Crank pulley that allow the mechanic to align Cam/Crank when putting the belt on.

Fortunately the engine is a 'Non-Interference' design, so you are not going to clash Valves / Pistons by having the timing out...
If you are going to drive it back to the garage, keep the revs low and stay off boost.

[paul port]

could be as simple as an intercooler pipe popped off

Not if the boost gauge is showing Boost!

[raptor95GTS]

You cannot correct Mechanical timing by rotating the distributor (Ignition timing)

Mechanical timing (Cams Vs Crank) is fixed by the cam-belt, and would be out if the cams were not correctly positioned when the new belt went on.

There are markers on the cam pulleys, Belt, and Crank pulley that allow the mechanic to align Cam/Crank when putting the belt on.

Fortunately the engine is a 'Non-Interference' design, so you are not going to clash Valves / Pistons by having the timing out...
If you are going to drive it back to the garage, keep the revs low and stay off boost.

hi paul, sorry I meant if the cams were out by a tooth then rotating the dizzy would fix the ignition timing relative to the crank. The mechanical timing would still be out - at least I think that's what was meant when my mechanic explained it too me when my mk1 was a tooth out on both cams - no power above 4.5krpm but the ignition timing was ok to the crank

[Harold]

Thanks for the advice guys. How would you tell whether it is mechanical or ignition timing that is incorrect.

[going4the1]

The ignition timing should not have been touched when the cambelt was changed.

The fault will be with the timing belt (mechanical timing). This can be confirmed by removing the upper timing cover. Your mechanic should be able to check if this is the real problem in 15 minutes or so.

[Harold]

Ok, picked the car up from the garage again, the mechanic said he had double checked the timing and that it was definitely correct and that he could not find a problem anywhere, i believe him as he does know his stuff and is very honest. I have taken the car back as the amount of misfire tells me it's something electrical, and unrelated to the cambelt change. Perhaps it's all an unfortunate coincidence.

The symptoms:
Rough idle - will drop down and up again continually.
Horrible misfire at about 3k rpm - a bit like hitting a wall, you can feel the car bucking, hesitating and does not sound healthy.
General lack of power under boost.

I replaced the rotor arm for a genuine toyota one at the weekend, as well as cleaning up the contacts on the dizzy cap (Paul Port copper one so just cleaned off some of the corrosion).
I had a quick look at one of the spark plugs and the tip was quite black (denso iridium, not sure how old they are).

So things to do/check:
Ecu codes
Replace spark plugs
Leads perhaps?
Coil - Where do i find this?
Map sensor - Again, not sure where this is.

I'm quite annoyed as when i drove the car down to have the cambelt changed it was perfect, pulled nice and hard with no misfire at all. Yet now it's a misfiring bag of crap.

Can you chaps suggest anything else i can check?

Thanks.

[paul port]

Honestly, it's still likely to be Mechanical timing. Print of the toyota BGB from ere
http://www.mr2-tech.com/bgb/mechanical/ ... anical.htm
although this is for a Rev1 engine.

That's a point... Worth double checking the correct belt was fitted - Rev1&2 is different to Rev3 - Number of teeth on the belt or something

[Harold]

Although that is for a rev 1 is the method of setting the timing on a rev 3 the same? I think I'll print out a copy and show it to the Mechanic to make 100% sure it's correct. I supplied the parts and bought them from tcb, though I didn't check to make sure it was the right belt, but I definitely ordered the rev 3 belt.

[ashley]

The timing marks are the same- yes. Basically the dot on each cam sprocket should line up to the ridges in the timing cover when the bottom pulley is at TDC (see page EM-40, point b.)

The only real difference in the method listed is that for rev3's+ the BGB suggests you install the intake cam pulley after you have the belt on the crankshaft and exhaust pulleys, but in terms of checking the timing the marks look the same to me.

It shouldn't be that hard to check yourself- you just need to undo the top timing cover and have a look. I've just done my NA rev 3, so if you want a hand checking I'd be more than happy to have a butchers at the w/e with you (I'm just north of Gloucester)

[Marf]

Ok, picked the car up from the garage again, the mechanic said he had double checked the timing and that it was definitely correct and that he could not find a problem anywhere

As Paul says, mechanical timing.

If he only checked the base timing with a timing gun etc then that will not show up if the belt has been installed incorrectly.

All your symptoms point towards the cam/crank timing not being correct due to incorrect belt fitment.

[Harold]

Ok, I'm going to check the timing myself, thanks for the offer ashman, if I can't get it sorted then I may take you up on that.

Thanks.

[Harold]

Have checked the cam timing and it's correct, the ignition timing however was out so we reset that to 10 degrees btdc. But the car was still misfiring, so we swapped the lambda out for a new one and the misfire is still there. So all I can do now is eliminate ignition components one by one, I have plugs and leads waiting to be swapped, It is a rather confusing problem.

The dodgy idle mainly seems to happen when the car is warm. And if I go up the revs gently the turbo won't kick in and I won't get misfire at 3k. But if I give it a lot of throttle then at 3k I get misfire, Whilst warm you can also notice a slight misfire through out the lower revs.

[Marf]

Did you check the belt matched up with the timing mark on the crank??

Top end mechanical timing might be fine, but if the bottom end mechanical timing is off you'll still have issues.

[Harold]

To check the cam timing all we did was turn the crank to top dead center and then checked the cams to see if the marks on the spokes matched up with the timing marks on the backplate. Does that sound like the correct process?