Technical Engine stalls when slowing to a stop

[aijosh]

Hello,

BACKGROUND:
-Timing belt broke.
-Changed belt.
-Engine started once and ran very bad. Refused to start after then.
-Mechanic said its bent valves so we replaced the bent valves.
-Engine works but begins to burn gallons of oil with lots of smoke from exhaust so I told him to change the valve seals on both the bent and ok valves.
-Engine runs ok now.

CURRENT ISSUE:
Engine stalls when I'm slowing down to make turns.

It usually stalls when I press down the clutch when the engine rev is almost at idle(1000rpm)

Some times it stalls at my regular driving rpm(2000rpm)

But the stall only happens when slowing down and I clutch down to disengage the engine.

Once I disengage the clutch the engine either stalls or rpm drops to almost 200rpm and recovers


:::: I some times mitigate this by waiting and clutching down right below the 1000rpm or clutching down at above 2000rpm and coasting till I brake.

NOTE:
The car idles ok. The idle is not rough or erratic although some times the idle rpm changes even after the engine has warmed up. But the change is not erratic. It very slowly drops to about 600rpm or rises to 1000rpm.

My normal idle rpm is around 1200rpm when the engine is cold and 800rpm when the engine is warm.

THINGS I HAVE DONE:
-Throttle relearn (lots of times)
-Confirm the engine timing and it looks pretty ok.

POSSIBLE SOLUTION I'M TRYING TO AVOID:

-Increase the timing: I was able to get the engine to stop this issue a long while back when the belt broke the first time and the mechanic timed the engine wrong.

I want to think increasing the timing would fix the issue but get me worse gas mileage.


SOLUTION:
This is where you guys come in.
Any advise is welcome?

 

[Ralf S.]

Ahhhh Ahhhh Ahhhh

I'm worried.

Can you tell?

If the mechanic changed the valves and didn't replace the valve stem seals, you need a new mechanic. Basically he was doing a job that cost you £300 in labour and didn't fit £20 of new seals when he had the engine in pieces in front of him and could have/should have seen there were poorly valve seals. Then I guess he charged you £300 again to do the same job he could have done properly the first time. It's pretty rubbish.

I doubt your problem is the valve timing.. (is the mechanic who "timed it wrong" the same guy who changed the valves...? Ahhhh Ahhhh ) since it idles okay and runs okay (I presume).

There's no such thing as "advancing the timing". There's "the timing". Nothing else.
If the valve timing is out, get someone else to re-set it to normal. If the timing is correct then advancing it or retarding it is a bodge that can wreck your engine and is not solving the actual problem.

Your rough idle and stalling is most likely to be an air leak, since you've just had the motor in bits c/o that ^^ fella Ahhhh Ahhhh. Check all the hoses from the air box to the inlet manifold and around the joint of the manifold to the head for any leaks. You can hunt for leaks by spraying some WD40 or penetrating spray on the joints with the engine running and looking for any sign that it's getting sucked in... but most of the time it's just a case of tightening any clamps or clips. Old hose clips may be stripped and fail to get tight. Get new ones.

Failing that, it could be the throttle position sensor (TPS). You need to remove the throttle body, clean out the MAF sensor (very carefully.. this is your mechanic Ahhhh Ahhhh we're dealing with).. then locate the TPS (it's usually the black box with wires to it, next to the throttle butterfly) remove it and clean the b'jesus out of it with contact cleaner or some other solvent spray. WD40 would kind of do but contact cleaner is better. Use a cotton bud or tiny bit of rag to wipe out any gunge or soot. Be VERY careful not to damage any probes or wires in there.

If you can get a diagnostic reading from the ECU then that might show a fault in the lambda sensor or the MAF, if these ^ other checks don't do it. Lambda is more likely to affect idling than the MAF so it would be my third thing to check, after leaks and TPS.


Ralf S.

 

[aijosh]

Thanks for responding. I just noticed your reply.

*Yes, I was charged all over again?. The mechanics here are crap so there isn't much I can do than live with it.

**No, I've stopped using the mechanic that timed it wrongly long ago.

***yeah, that is why I prefer not to advance the timing cos that wouldn't solve the underlying issue

****Well, as regards air leaks, there was a major one that was patched after the repair. (I think the hose that returns vapour from the fuel??? Its close to the MAF sensor). The stupid mechanic just broke stuff around the manifold.

I'll recheck to see if it is leaking.

Also he broke a part of the intake manifold.

(There is a tiny hose that runs from below the area where the engine oil cover is. The hose runs over the "cam head" but under the "manifold" then plugs into the back of the manifold closer to the throttle body than the MAF sensor.)

And instead of finding a fix, he just glued the opening on the manifold shut and glued the hose shut too. I'll attach a picture once the day is bright.

I'm now guessing this is where the issue is. I'll try and see if I can open up the sealed holes and connect the hose to it cos the other solution is to buy another manifold which...I'm done spending so much fixing this car.

*****I have a Bluetooth OBD II reader. It always gives me a TPS error. P1220. I've cleaned it and the error goes away but still comes back after days of driving

 

[aijosh]

Picture

 

[jsp]

uhh is the timing belt on time?

 

[aijosh]

Yeah. It is. I should probably check again to see if it somehow has moved.

I have bought two other throttle bodies but with different behavior on each one.

The newest one I bought would work of for a while then the engine would judder and shut off with a P0101 code. I also bought another MAP sensors but the P0101 shows up on both sensors when this throttle body is in use.

Using the older throttle body, I get a P1220 code but the engine never shuts off. The only issue with this body is the car doesn't rev past 3000rpm.

So I'm just using the old throttle body as it seems to be the better evil