S3 engine problem: running badly at high revs

[SamHH]

Hi,

Posting on behalf of a friend who has a 1990 S3 which isn't running smoothly and who would like any suggestions of how to fix it. I'm not familiar with the technicalities so I'll just give his description to me of the engine and the problem:

The oil pump seized and broke the original engine so he had it rebuilt with parts from a donor engine (2.9l Ford Cologne) from a Ford Granada Scorpio 4x4. The block, pistons, oil pump and cam from the Granada engine were used with the heads, exhaust manifold and sump from the original TVR engine. A new water pump, head gaskets, clutch kit and distributor were fitted.

The rebuilt engine now runs smoothly at low engine speeds, but when it reaches approx. 3500rpm it "hits a brick wall" and won't rev any higher. He returned it to the person who rebuilt it, who got it running smoothly at high revs by altering the ignition timing but it then wouldn't run smoothly at low revs. He's also taken it to an engine specialist who've been unable to diagnose the problem (see attached images of their report). One other thing is that the exhaust manifolds are glowing red hot, which he thinks is wrong.

Any ideas?

[Tant]

Presuming it got a clean bill of health on all of those tests, and considering the manifolds glowing red, I'd suspect that either the ignition timing is way off, or somehow they have got the cam timing off somehow. Both should be very easy to check.

I presume the injector checks were OK? Have the emmissions been tested at either low or high speed? I'd also, just for the hell of it, try another coil and another ECU, just to rule those out. I'd make sure it is not running lean and detonating...can you hear it "pinking" under any sort of load? I'd also check for inlet system leaks, and that the breather pipes are all clear and unobstructed.

Hope that helps
Cheers

Ant

[ketvrin]

Sounds like timing to me and I wondered if the ECU was placed in "reset/service" mode before the timing was done ?

K

[SamHH]

Thanks very much. I'll pass that on to him. I don't know about what was checked by the engine specialists, but he says that everything they did check was fine.

Apparently the cam (which was from the donor) is slightly unevenly worn, and my friend suspects it is not the same type as was in the original TVR engine (correct?), but they don't believe either of these things could cause the problem.

[ketvrin]

another thought was there are two types of ECU IIRC, are you sure the engine ECU combination is a good one ?

look here too...

http://www.fordscorpio.co.uk/faultfinds.htm

let us know how he gets on and tell him not to be shy and join the forum (and list his car on the Owners List ?)

good Luck

K

[Tant]

Just a thought....was the engine from an autobox car? The cam may be different in an auto engine, although I wouldn't expect the engine to run as badly as you describe. It might be worth checking the cam lift with the engine in situ....this will also tell you if the cam is worn below acceptable limits.

[tvrgit]

I'd go along with the suggestions of ignition timing or cam timing being out.

I believe TVR used the original ford cam etc - it was absolutely bog standard Ford Granada / Scorpio, so I would doubt if there's anything amiss there.

With regard to Kevin's suggestion of the ECU being incompatible, that could be a possibility - the later Granadas (and the S3Cs and S4s) had catalyts and lambda sensors, whereas the earlier cars were programmed to map fuel ratios from air flow meters. The ECU is therefore bound to be looking for different inputs, and giving different outputs, from a non-catalysed car. I don't know if the ECUs were programmed differently, but it's possible that using a cat-car ECU with a non-cat engine (or vice versa) could give problems.

The other possibility (with the exhausts glowing red-hot) is that the car is being grossly over-fuelled, and burning is still going on as the gas is expelled to exhaust. That again could be the ECU, or an injection problem. I dodubt that though.

[tvrgit]

Tant said:

Just a thought....was the engine from an autobox car? The cam may be different in an auto engine, although I wouldn't expect the engine to run as badly as you describe.

I think the manual and auto engines were exactly the same (although again, the ECU program may have been different because the auto would have to pick up kickdown signals etc).

Don't know though, but I've never heard of them being different on the Granada )I had a Granada Auto before the S!)

[Barkychoc]

My totally wild guess - a partially blocked exhaust (Centre box fell to bits inside?)

Not enough flow for high revs and causing that heat build up - but enough flow for low revs.

Additional thought - has it got cats? Cats collapsed?

Edited by Barkychoc on Tuesday 4th January 19:40

[tvrgit]

I've just read the test report properly and see that they have reset the valve clearances. Don't want to cast aspersions, if they know what they are doing, but did they check first that the block is not off a "hydraulic tappet" car? If the cam has hydraulic tappets, and they have adjusted it as if the tappets were solid, the valves won't be opening anywhere near enough and engine breathing will be totally buggered.