Misfire & no power

[fester001]

Its me again! now have a new problem my 90 525i It only started when the missus took the car to work by the time she got there it was running rough on idle and refusing to accerate. I took it out on her return & sure enough it was idleing very badly when trying to accelerate it died and misfired. Chatting to a local mechanic he suggested it sounded like an inlet manifold leak! What do yo reckon?

Any advice from anyone who has had a similar problem & what the cause was would be greatly appreciated, as well as how difficult this job would be for a reasonably competant mechinic like me to do!

[witeshark]

Have you looked the intake over for cracks? In any event, there may be other issues since intake cracks may tend to affect idle more then higher engine speeds. I have check of the fuel system, filter and pump(s) etc.

[fester001]

Thanks for that I have now replaced the fuel filter, fuel pressure regulator, spark plugs and the O2 sensor. The O2 sensor after having my error codes read.
The car is now idling well, but on acceleration it still loses alot of power & splutters & backfires. on reading the error codes after clearing all the old codes I rechecked the code and is still thowing up an O2 fault! This is a brand new sensor not cheap.my mate says its a timing or plug lead issue but I am more inclined to think it could still be an inlet manifokd leak!
any further help would be appreciated. Also it only does it under load never when static
please help i need this as reliable transport
Thank you

Simon

[jimoreno]

O2 codes usually mean that there is something wrong in the mixture (lean/rich) and the sensor could not correct it. You need more information! You might have a vacuum leak somewhere allowing unmetered air into the engine but the ECU cannot compensate for it. Since you have a 525 look for leaks in the air intake bellow (cracks) or any disconnected vacuum hoses.

[fester001]

Thanks the the advice I have checked those out the pipes appear to be ok no cracks or the like, I did notice that the metal pipes going into either side of the throttle body as well as the rubber pipes are all loose! so I am going to reclamp and put sealant on all the joints & hope this will help the problem. Otherwise as i mentioned before how about an intake leak?

I prefer that idea to my mates who wants to start messing with the timing!This is becoming a pain in the arse as it will only do it when trying to accelerate not even harshly.

I will report back the result when i have done it!

[fester001]

Ok I have done all the air pipes ans seem fine while running the car up and sorting things out I heard the apparent backfiring noise cpmeing from the airbox, with the airbox visible moving as it did it.
Would this indicate the Mass Air Flow unit as no codes has shown up on the display!
Please any help will be much appreciated.

[jimoreno]

That is a backfire so it sounds liek your friend is right abiut the timing issue. The problem is that timing is controlled by the computer so there is no manual adjustment. I think that you need to talk to your "missus" and find out if anything was done to the car liek adding fuel, driving through a water puddle, etc. I'm all out of ideas!

[fester001]

Thanks for that I am a total loss to. I read an old thread that had someone with the same problem terns out that he had run out of fuel at some point and the pick up gauze had become blocked so will give that a try as its freethen maybe plug leads also if its possibly a timing issue how about the CPS?

I am quickly starting to hate this car people rave about them but I have had one problem after another Any other input will be gratefully received.

[fester001]

Well I finally got to the bottom of it! On removing the fuel pump I found the whole top had blown off!!! (the area that is crimped to hold all the internals in)

I see why it was getting so bad now, no idea what would do that to the pump but I shall be replacing the regulator that screws on top as well!

[witeshark]

Very glad you got it sorted!