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[Andy_XR2i]

whats the best way to test the engine temp sensors and what ranges do they operate in?

My 16v 2i's zetec seems to be having issues again! jerky and awkward below 2.5K rpm, looking at the output from the lamba sensor, it can go radically lean for a few seconds, throttle feels flat as a pancake, unresponsive, then the reading suddenly flies high as compensation a couple of seconds later and as a result, slightly less flat but still rough running for a few seconds.

This only seems to happen on mild throttle accn. and more when warming up, but the whole car feels kind of strangled and jerky below 3K rpm.

It's the second TPS I've tried, the throttle body is off the 2.0L but other people using this dont seem to have this problem. Only other mod is a straight through exhaust, cats still there.

Anyone spot anything that sticks out as a possible cause?

I'm thinking bad fuel pressure maybe? iffy temp sensor?

from the lambda display the A/F ratio looks ok, apart from when it seemingly shuts off(!) so im a bit lost!!!!!

Andy

[Project]

Possibly that your ECU thinks it still has the original (smaller) TB and therefore less airflow going into the engine. Following this line, the increased size of the throttle body would be more likely to cause the inlet manifold airflow to stall, and the ECU is probably undercompensating before overcompensating.

In any case, the only thing I could suggest is to (a) try swapping the throttle bodies back, temporarily, and (b) get it rolling roaded.

Al

[Excursion]

Teh alrger throttle body is LESS likely to cause air stall due to the free flowing nature of it. The smaller one changes the shape of the airflow, causes turbulence and therefore a slow in air speed.

Zetecs run froma MAF so can account for many engine changes - the 1600 ECU will run the 2 litre no probs.

It sounds like ur o2 probe is fobed andy

[Project]

I would listen to Mark.

The tb prob I imagine is that the sudden lack of resistance in the inlet manifold tract would equalise the pressure in the tract to the outside environment much faster, causing the airflow to slow rapidly and causing a similar situation to that in turbofan engines where the airflow through the compressor blades stalls and normal physics rules no longer apply as they should.

Boring sod, aren't I?

[Excursion]