Author Topic: Gradual throttle & it runs fine, but if you flog throttle, it falls flat on its face (Read 4528 times)

Joerdan23TN · « **on:** June 27, 2012, 04:37:34 PM »

First post here! been lerking a while. I hate we have to meet under these circumstances but oh well!

stomp code 1222

Its running rough, cold starts arent terrible but rougher then norm and it kinda sounds like its missing. RPM's seem to studder at lower rev ranges.
I notice a considerable loss in power. I am given it the same gas I would normally give it to get on it just to keep up in traffic from stops.

I bought some new plugs, installed and no better.
I found a spark plug wire boot with a crack in it.. electrical taped it and coated in epoxy to get me by until i can afford some new ones as Bosch sets are expensive. This helped some but not my real issue.
I have visually checked all hoses for Vacuum leaks and hit them all with Carb cleaner just to double check. No issues found.
The little grey plug used on cars with no O2 sensor is unplugged.
It has a new fuel pump assembly (2 months old)
Last night I replaced the fuel filter.
Cleaned the ICV (was a bit dirty on out flow side)
Cleaned boot.
Cleaned the TB

02 sensor? But I dont think that is the problem as removing it while the engine is running does make some difference (raises idle some, revs still stutter) , letting me know its working. riight! if it was bad the engine would be the same letting me know its making no difference? is this thought right?

Im at a loss right now... whats left...?

Injectors, possible jump timing? me no know!

I forgot till today that I should check the FPR, I will do that later on today if time allows (
I have only had the car 6 months and have really enjoyed ownership and the driving experience. But its my first car none GM, no carbed, none ECU'd.

I think im doing pretty good trouble shooting but as of now I really need some direction.

mr ilia · « **Reply #1 on:** June 27, 2012, 06:41:49 PM »

Vacuum leak, I'm 90% sure. Do the clean up under the intake (good write up can be found on this site).

If you suspect this is O2 sensor, try unplugging it if nothing changes, then it is not the sensor.

Found the link, but this is from another site.

http://www.r3vlimited.com/board/showthread.php?t=253698

DesktopDave · « **Reply #2 on:** June 27, 2012, 08:24:59 PM »

1222 is an O2 code, but it usually means a manifold leak. I usually start with a little spray testing...with the car idling, spray some WD40 around the intake gaskets and the injector o-ring seals. Idle should change if the WD40 finds a leak.

Less likely but still possible is a bad TPS or injector. I use a long screwdriver as a mechanic's stethoscope to test the injectors - blade on the injector body - put the other end in your ear...you'll (hopefully) hear them clicking merrily away at idle.

You might also have troubles with the intake or coolant temp sensors...you'll need a meter for testing them.

Worst leak I found on my car was the main intake and ICV hoses - cracked on both ends, especially that hidden junction right under the intake manifold. BMW went crazy with preheating the intake air...not sure why, it's a definite Achilles' heel on our cars.

Considering that you're coming from carbs (I've owned a bunch myself) - get yourself up to speed on a digital multi-meter and download the BMW Electrical Troubleshooting Manual (ETM)...it'll eliminate guesswork...great tools to have.

bmwman91 · « **Reply #3 on:** June 28, 2012, 02:33:22 AM »

If you had a cracked ignition wire and putting some make-shift insulation on it improved things, then I would say that you should put new ones on. The voltage in those peaks at 25,000V, and damaged ones can arc and have all sorts of nonsense. If a cylinder is misfiring, it will cause the O2 sensor to read very lean since one or more cylinders has lots of unused oxygen pouring out of it.

Next, I would check the fusible link in the trunk. It has been getting more and more common for people to have it corrode or break, and when that happens the fuel injection system either loses power, or runs off of like 6V. It is on the smaller of the two black positive wires coming off of the battery, about 18" away from it. Cut the sheath off of it to check. You can wrap it in electrical tape when done.

When you checked the vacuum hoses, did you also check those fittings down under the throttle body. Those molded rubber splitter things are notorious for breaking open, particularly the one that the valve cover hose connects to. Get down in there with a flashlight & mirror to check it out. I bypassed that fitting entirely with a piece of vent hose from the local parts store.

Did you check the little vacuum line that runs to the fuel pressure regulator? If that popped off you would have weak running.

E36Coupe · « **Reply #4 on:** July 01, 2012, 07:32:22 AM »

if u give it gentle throttle up to half and its okay, but falls flat on its face under full load, then goes again if u back off...

i work in a busy garage in the south of the uk, and 99% of the time this sort of behaviour appears when your Mass air flow sensor is giving faulty readings to the ECU.

also, when this happens it can throw up o2 sensor faults (because the car is running very lean). its quite common on a lot of injection cars, not specifically BMW's. had exactly the same thing on Fords, Vauxhall, Mercs etc.

very rarely does a MAF sensor actually bring up a MAF sensor fault, but personally that is where i would start.

EDIT: sorry forgot to mention, ON Bmw's it is also very common for the Intake hose to split between the MAF and the manifold, you dont see it, but when you floor it and the engine moves but the airbox is bolted to the car, the hose takes the movement and splits, causing a kangaroo behavior and bad idle, also lean running and o2 codes etc.

because the Air is entering the engine After the MAF sensor, it gives the ECU a false reading, and doesnt throw in nearly enough fuel, hence falling flat on its face...

Joerdan23TN · « **Reply #5 on:** July 09, 2012, 04:37:58 PM »

Mess under intake complete!
New Fuel Filter, Cleaned MAF.

Car still bogs down @ WOT.

Any suggestions before I take it to Autohaus tmrw.

Thanks for all the help!

e3016v aus · « **Reply #6 on:** July 28, 2012, 09:27:05 PM »

unplug the maf and test it. if its the same as it was before thats your issue

doitover · « **Reply #7 on:** July 30, 2012, 09:11:25 AM »

fuel pump?

kimmerkaze · « **Reply #8 on:** August 01, 2012, 09:07:34 PM »

I also have similar symptoms but not as bad as OP. Would be great to hear what OP finds out!

I'm waiting for my FPR to arrive. Besides that, I'm trying to get another ICV. Fuel pump also waiting to be installed.

Will check injectors and alternator for now

bimma_318iS · « **Reply #9 on:** November 08, 2012, 01:05:00 PM »

If you have found the solution, please us know. It will be very helpfull for future reference...and I am dying to know