backfire and loss of power - BMW Forum

nadeemkhan · 02-22-2009, 06:13 PM

my 91 525i backfires and looses power on fast accelerations, uphill and around 50/55 mph. I had complete tuneup done with brakes and roter changed but no improvement...

johnnyBgood · 02-22-2009, 07:08 PM

Quote:

Originally Posted by nadeemkhan

my 91 525i backfires and looses power on fast accelerations, uphill and around 50/55 mph. I had complete tuneup done with brakes and roter changed but no improvement...

I would start by checking for leaks around the MAF Sensor, mainly around the intake boot, they are prone to dry out & crack, causing leaks! Also, I would try cleaning the MAF Sensor.....

http://i70.photobucket.com/albums/i9...s/b338c8e0.jpg

e36-tech.com | CLEANING YOUR Mass Air Flow Sensor DIY

johnny,

nadeemkhan · 02-22-2009, 11:18 PM

Thank you Jonny! that's lots of help especialy with pictures... I'll try it this weekend.

emiliomax · 02-23-2009, 09:44 PM

That is a cool idea Johnny. I'm also gonna try it tomorrow. I've been getting some misfires and hesitation when I first put it in gear. Thanks

nadeemkhan · 03-26-2009, 01:07 AM

...so I took it to a mechanic who found a bad coil and a bad hose. Both have been replaced. The car starts but runs very poorly feeling it is going to run out of power. Mechanic thinks it is the feul pump... Tomorrow, he will test the pressure and let me know for sure if it is the pump...

oldschool93 · 03-26-2009, 01:19 AM

hey, try cleaning the ICV, its a common problem with an easy solution

nadeemkhan · 03-26-2009, 12:38 PM

What is an ICV and where do I find it? Last summer it had a complete tuneup and the fuel filter was replaced...

oldschool93 · 03-26-2009, 02:57 PM

Idle control valve, I am not sure where you would find it on your engine, here is a thread, there is no pics but thats what i followed to clean mine and i did fine. ICV cleaning instructions for E39 - Bimmerforums - The Ultimate BMW Forum

this one shows more pics but less explanation:
ICV Removal

i hope it works

nadeemkhan · 03-26-2009, 10:11 PM

Thanks OldSchool! I'll try it when I get the car back this weekend. The mechanic couldn't test the fuel pump and he has given up after trying the following things:
Pull/replace spark plugs
Pull/Bench test coil packs and replaced 1
Checked wires, vacume hoses, MAF, intake for leaks/shorts
R&R (not sure what it means)
Clean MAF
Replaced air filter
Rewired ground to 6 coil packs
Chcked individual wires to coil packs and injectors
R&R IAC hose

oldschool93 · 03-26-2009, 10:50 PM

oh wow. you trust this mechanic? i cant belive he woudlnt think of this. give it a try and let me know how it goes. good luck.