stator Posted September 16, 2018 Report Share Posted September 16, 2018 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. Quote Link to comment Share on other sites More sharing options...
Rich Posted September 16, 2018 Report Share Posted September 16, 2018 There's a fault in that department, doesn't mean the sensor is at fault. Quote Link to comment Share on other sites More sharing options...
mk2 Posted September 16, 2018 Report Share Posted September 16, 2018 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. Quote Link to comment Share on other sites More sharing options...
Pete Posted September 17, 2018 Report Share Posted September 17, 2018 Brake cleaner is your friend. Quote Link to comment Share on other sites More sharing options...
mk2 Posted September 17, 2018 Report Share Posted September 17, 2018 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. Quote Link to comment Share on other sites More sharing options...
Pete Posted September 17, 2018 Report Share Posted September 17, 2018 Brake cleaner is cheaper😂 Quote Link to comment Share on other sites More sharing options...
Pete Posted September 17, 2018 Report Share Posted September 17, 2018 Saying that I’ve got a decent vac tester and diag machine at home that I’d probably use first if it’s raining. Quote Link to comment Share on other sites More sharing options...
stator Posted September 18, 2018 Author Report Share Posted September 18, 2018 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 Quote Link to comment Share on other sites More sharing options...
Pete Posted September 18, 2018 Report Share Posted September 18, 2018 What engine is it and what codes? Quote Link to comment Share on other sites More sharing options...
mk2 Posted September 18, 2018 Report Share Posted September 18, 2018 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. Quote Link to comment Share on other sites More sharing options...
Rich Posted September 18, 2018 Report Share Posted September 18, 2018 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. Quote Link to comment Share on other sites More sharing options...
stator Posted September 19, 2018 Author Report Share Posted September 19, 2018 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. Quote Link to comment Share on other sites More sharing options...
Pete Posted September 19, 2018 Report Share Posted September 19, 2018 Maybe the repair didn’t last? But I’d definitely be checking the wiring to the sensor from the ecu. As has been suggested. Quote Link to comment Share on other sites More sharing options...
stator Posted September 19, 2018 Author Report Share Posted September 19, 2018 I couldn't even identify the wiring from the ECU to the sensor to check it Quote Link to comment Share on other sites More sharing options...
Rich Posted September 19, 2018 Report Share Posted September 19, 2018 Fortunately for you it is all colour coded. Quote Link to comment Share on other sites More sharing options...
Pete Posted September 19, 2018 Report Share Posted September 19, 2018 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. Quote Link to comment Share on other sites More sharing options...
Rich Posted September 19, 2018 Report Share Posted September 19, 2018 Take the battery out and look under the tray. Quote Link to comment Share on other sites More sharing options...
Sausage Posted September 19, 2018 Report Share Posted September 19, 2018 Does it go into limp mode or is gutless? Codes would be useful too. Quote Link to comment Share on other sites More sharing options...
Pete Posted September 19, 2018 Report Share Posted September 19, 2018 Sausage is a sausage. Quote Link to comment Share on other sites More sharing options...
mk2 Posted September 19, 2018 Report Share Posted September 19, 2018 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. Quote Link to comment Share on other sites More sharing options...
stator Posted September 19, 2018 Author Report Share Posted September 19, 2018 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. Quote Link to comment Share on other sites More sharing options...
stator Posted January 2, 2019 Author Report Share Posted January 2, 2019 The main problem was the throttle body butteryfly valve sticking when the engine was cold. Cost quite a lot of money to diagnose and fix in the end, but now my car should pass the MOT next year Quote Link to comment Share on other sites More sharing options...
mk2 Posted January 2, 2019 Report Share Posted January 2, 2019 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........ Quote Link to comment Share on other sites More sharing options...
Skezza Posted January 7, 2019 Report Share Posted January 7, 2019 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. Quote Link to comment Share on other sites More sharing options...
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