Technical help desperately needed

[OldKingPole]

Why does my car go like f**k when its cold and lose power when it is hot?

I am reaching the end of my tether with this problem now and begging for advice. I've replaced the fuel pump, the FPR, N75 valve, the coolant temp sensor on the back of the head, i've changed the barometric sensor, and the ECU has been to S2Central.

I'll get a rotor and cap during the week but i dont expect much from that. Plugs are Bosch and good condition, leads are new and tested. I haven't performed a boost leak check yet. But waiting for a reply from Andy P.

What else can affect the car's performance as it warms up? Its a 3B.

Any input would be greatly appreciated. Ive stuffed it in the garage now, out of my sight in disgust.

[newsh]

How many miles on the motor?

[OldKingPole]

145k - ish. Are you thinking rings? Its interesting you should say that. I'll perform a compression check on it now, just to rule it out...

[20Vcqdriver]

I am watching this one as mine is similar though usually in hotter weather and been told it might be the IAT in the top of the inlet manifold and that its in a piss poor position so thinking of moving it to just after charge cooler....

[Tonks4x4]

I take it went like stink when you tried it first thing?

Try unplugging the MFTS plug off the water rail and take it for a spin see if that cures the problem.

[OldKingPole]

I am watching this one as mine is similar though usually in hotter weather and been told it might be the IAT in the top of the inlet manifold and that its in a piss poor position so thinking of moving it to just after charge cooler....

Yeah, i think i saw your thread when i was searching. Whats an IAT? Is that the little sensor with 2 wires coming off it on top of the manifold?

Brian, it did mate. On only 12psi of boost (or that is what the gauge was showing). Get it warmed up and the boost seems to go up but without the benefits. I'm feeling a road trip coming on soon pal.

[20Vcqdriver]

Yeah, i think i saw your thread when i was searching. Whats an IAT? Is that the little sensor with 2 wires coming off it on top of the manifold?

Brian, it did mate. On only 12psi of boost (or that is what the gauge was showing). Get it warmed up and the boost seems to go up but without the benefits. I'm feeling a road trip coming on soon pal.

IAT is the Intake Air Temp sensor. Know someone with a 10V ur who moved his and made a very noticaeble difference, so going to move mine too. If you are in stop start or slow traffic the manifold and sensor get hotter and hotter so that the ECU alters its settings thinking you are sucking in hot air, then when you floor it, no power until the sensor has cooled from the airflow and the ECU re-adjusts its values. Going to fit mine below the water injection nozzle and a foot from the chargecooler exit... Fingers crossed.

[Jamo]

I take it went like stink when you tried it first thing?

Try unplugging the MFTS plug off the water rail and take it for a spin see if that cures the problem.

The 3B doesn't use the MFTS for boost alarm only the ABY / ADU according to S2central

[S2central.net]

Get a meter and measure electrical resistance of the 2-pin IAT sensor... its just a thermistor... resistance changes with temp... and ECU adapts fuel & spark accordingly. It decides a nominal number in the event of disconnection / total failure... but funny running could arise if it gets haywire values when hot vs cold. Try and measure it cold and after a run... you can drive car without it too and see if substitution is better.

I had a 3B loom in here this week for repair and pin for pin examination... The MY91 3B DOES use MFTS-R pin signalling into ECU pin #36. This appears on schematics and was reflected in reality on this MY91 loom - there is easy way to spot it.

MY92/93 schematics for 3B however show that MFTS R-pin is unused as far as ECU is concerned... just connects to aircon where applicable.

[S2central.net]

Just to add... I am trying to find time for a detailed documentation on the 3B loom - much like the ABY analysis that I did a while back - takes fracking ages to do it nicely so patience please !

[OldKingPole]

Thanks Paul, i'll add that to my list of diagnosis for the weekend. Watch it p155 down!
Interesting remark about the 3B loom 1991, as that is what it all came from, S2 on a J plate. So that little sensor falls under the fire of scrutiny...

[S2central.net]

Whether the thing is all wired up properly though is another matter.

That spring is too stiff if you get 12psi with a boost cut
Or n75 unplugged.

[OldKingPole]

I take it went like stink when you tried it first thing?

Try unplugging the MFTS plug off the water rail and take it for a spin see if that cures the problem.

I know the sensor you mean but what does MFTS stand for?

[S2central.net]

Multi function temp sensor - my site explains it so do some others of course - it is not unique to s2

[OldKingPole]

Whether the thing is all wired up properly though is another matter.

That spring is too stiff if you get 12psi with a boost cut
Or n75 unplugged.

No boost cut Paul. Not had a boost or fuel cut since the homefry. Before then it was random. N75 is not unplugged. No fault codes when pulled on saturday.