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Diagnostic / ECU specialist in Plymouth area


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Anyone know a specialist in the Plymouth area who can help me sort out my annoying 17 year old Lupo?

Map sensor error comes on every few minutes. Garage say there's nothing wrong with anything. Sensor replaced a couple times.

So I need it fixed before the next MOT next year.

Need someone reliable, worried I'll find someone who will waste hundreds of pounds not fixing the problem.

 

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Probably a manifold/air leak downstream of the throttle. You usually get this fault if at idle on a warm engine, the vacuum is too weak. ie, air is getting in somewhere. Sensor reporting a plenum vacuum that should be stronger, but isn't. So looks like the sensor is messing about. Try blocking off any sources of external air temporarily. Like brake servo feed.... those vacuum pipes do have a tendancy to crack/split at the joins.

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Never thought of using that... i always use a tank of propane with a hose. 

@stator the extra air mixed with extra fuel (gas/solvent whatever) makes the engine rev up when it has more mix to burn :)

when it revs up, you've found the leak.

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Thanks for the tips, but they're beyond me to be honest.

The manifold leaks were all repaired by the garage previously, the error has not gone away.

That's why I'm looking for someone who can diagnose the fault or replace the ECU etc

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Just had an idea... it is possible, that the ECU internal fault diagnosis thing is getting mixed up.

It's probably backing off the idle air circuit (which controls the idle RPM) if there is a leak (still), and it's picking up the O2 sensor readings as the mixture being too lean. As in, too much air compared to the amount of fuel that the ECU has decided it needs for a steady idle. It knows what sort of injection timing is normal at idle, and is probably running at "end stop".

But. It is possible that poor fuel flow is also resulting in a lean mix. Fuel filter? Pump? Hose leak? Fuel pressure regulator? Vacuum connection? At full throttle, is there a lack of power after a few seconds? = fuel problem.

I doubt there's an ECU fault. The vac test concept shows how well the engine is sucking in air. The higher or stronger the vacuum at idle with hot engine, the better the thing is running. Engines that can run with really strong vacuum at idle are usually very efficient and generate loads of torque. So the vacuum level is a good indicator of engine condition.

The MAP (inlet manifold absolute pressure) sensor measures the vacuum level to work out how much air is available. Then the ECU works out the right amount of fuel to inject, based on RPM, coolant temp, air temp, ambient air pressure, load demand and previous cycle exhaust result (O2 sensor). If the previous result is out, it tries changing injection amounts to get back to the result it's looking for. 

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I'd even contemplate testing the wires with a continuity tester in case it is rubbing somewhere.

Sometimes under the battery.

If the timing was off they do throw up codes in odd places.

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It's the 1.4 16V AUA engine

Error code is this one

http://wiki.ross-tech.com/wiki/index.php/17566/P1158

 

It's been happening for 5 years, to varying degrees. There were some leaks in the manifold which caused problems and were repaired. The error went away for 3 months.

But most of the time it causes no problem at all. Engine always seems to have full power.

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Yeah, pull the shroud back from the sensor and the cables with have colour codes, then look for the same colours at the ecu end and check for continuity. Saying that though if it’s intermittent you can’t guarantee a faulty reading, could do with a proper test point kit and then wiggle the loom about.

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My bet is that there still is a leak from what's been said. Probably used the latest formulation hylomar blue sealant on the gasket face which is new, different, and environmentally firendly. It's been ruined. Get some high temp silicone.

yeah, if MAP was completely wrong, it'd probably be gutless and run in some sort of limp mode. If it's ok at full throttle, that tells me that it only happens at high vacuum. Idle. =Leak.

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It hardly ever goes into limp mode. It's done it once or twice in 5 years. Restarting the engine immediately always fixed it.

When it had a real leak, it started thumping on gear changes, as it's an automatic transmission.

 

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  • 3 months later...

Sump blow by gases cause so many many problems with fuel injected engines. I just wish there was a solution other than diverting everything down towards the road.

When an engine sucks clean fresh filtered air, it runs so much cleaner, more efficiently and smoother. As soon as oily hydrocarbon waste contaminents are introduced, air valves get clogged, the backs of the inlet valves build up crusty gunge, catalytic converters get poisoned, vacuum systems get blocked, EGR starts to stick, throttle valves build up stickyness, MAP sensors misbehave... the list just goes on and on.

Every car/truck/thing I ever get my hands on, I divert the blowby gases. Result is an engine that never ever lets you down (unless there's a component failure). The emissions from my 'dirty' diesel SDIs are always well below the 0.7 limit (set by the little compliance plate in the engine bay). Almost fresh air. Modern diesels they now MOT test to the 2.5 limit and they still fail........

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On 1/2/2019 at 9:54 PM, mk2 said:

Sump blow by gases cause so many many problems with fuel injected engines. I just wish there was a solution other than diverting everything down towards the road.

When an engine sucks clean fresh filtered air, it runs so much cleaner, more efficiently and smoother. As soon as oily hydrocarbon waste contaminents are introduced, air valves get clogged, the backs of the inlet valves build up crusty gunge, catalytic converters get poisoned, vacuum systems get blocked, EGR starts to stick, throttle valves build up stickyness, MAP sensors misbehave... the list just goes on and on.

Every car/truck/thing I ever get my hands on, I divert the blowby gases. Result is an engine that never ever lets you down (unless there's a component failure). The emissions from my 'dirty' diesel SDIs are always well below the 0.7 limit (set by the little compliance plate in the engine bay). Almost fresh air. Modern diesels they now MOT test to the 2.5 limit and they still fail........

My SDI also never failed an MOT on emissions. They are one of the cleanest diesels you'll come across.

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