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View Full Version : Still slight hesitation after fixing the intake boot?


Interceptor
10-04-2005, 12:52 PM
As some of you might know, I've been fighting this problem for months now.

The simptoms are following:
- slight hesitation at lower RPMs (<1500)
- slight overall loss of power
- above average fuel consumption

After I fixed the rubber boot it got a lot more responsive, but it's still not quite right. Before this problem occured, I could start moving by just releasing the clutch moderately and the rpms would not drop. Now when I try that, it lowers the rpms a bit and then resumes. And another thing - when I put in reverse and let the car roll on it's own without any throttle applied, the movement is a bit jerky, not smooth like it used to be.

I've recently changed the following:
- oil (engine, brakes, gearbox & final drive)
- filters (oil, air & fuel)
- fuel pump
- injectors
- spark plugs (Denso Iridium - but the problem existed before them)
- intake boot + 2 vacuum hoses

Any help/tips/suggestions from the experts?

P.S. What's the other hose (the longer and wider one) that connects to the rubber boot for? It's not shown in the same picture with the rubber boot, only the smaller one is (see pic). Both the hoses connect to the rubber boot using plastic connectors and are located on the lower end of the rubber boot near the throttle body.

http://www.realoem.com/bmw/showparts.do?model=HD51&mospid=47375&btnr=13_0381&hg=13&fg=15

I would have taken pictures but it's raining as hell here for the past few days and I do not have a garage :(
Jeff N.
10-04-2005, 12:59 PM
Have you done Shogun's famous ECU reset? I suspect the system will need to retrain itself now that the leak is corrected.
632 Regal
10-04-2005, 02:05 PM
yep... reboot it and change out them crappy plugs.
Interceptor
10-04-2005, 02:21 PM
yep... reboot it and change out them crappy plugs.
Tried the reboot - after some time, same thing started happening.

Regarding the plugs - the same thing was happening BEFORE I installed the new ones, and I have a friend using them in his 320i M52 without any problems so I don't think they're the one to blame. Altough, I might swap them if I get desperate enough.
tnt525i
10-04-2005, 02:45 PM
check your O2 sensor, that usually causes poor performance, just my 2cents, hope you get it solved
632 Regal
10-04-2005, 05:07 PM
lose them crappy plugs and then reboot.
uscharalph
10-04-2005, 05:13 PM
lose them crappy plugs and then reboot.
I use the standard Bosch Plus plugs
SRR2
10-04-2005, 05:28 PM
Are you talking about the thing where he says to run up to 5000 RPM and take your foot off the gas a couple of times, then let it idle for five minutes? If so, that's only for engines where there's two throttle bodies that need to be sync'd up. Otherwise, you can reset the adaptation by simply disconnecting the battery for five or so minutes. It's an urban myth that you need to put the key to II and connect the battery leads together (NOT the battery itself! -- I always feel the need to stick that in when the subject comes up) to reset the elex. It simply doesn't take that long. The ECU will reset in a matter of seconds. Actually, the easiest way to do it is to open up the elex box cover and pop off the ECU connector. Give it a minute and put it back on. Avoids having to pull up the seat, if that's the battery situation you have, and takes only a couple of minutes.
Ali
10-04-2005, 07:41 PM
Had a similar problem in my car turned out to be vaccum leak, check around all ur vaccum pipes especially in spots which aren't so easily visible, after u find ur leak (it could just be a pipe which wasn't tightened enough) do a reset.

Ali
Dash01
10-05-2005, 11:23 AM
Ditto the vacuum leak theory: Be sure to double-check the pesky but hidden vacuum tube on the under side of the intake manifold. It gets lots of heat from the engine, so the rubber tends to crack over time, especially at the nipple. New tubing costs a few cents and is available at any car parts store.
Interceptor
10-05-2005, 11:31 AM
Ditto the vacuum leak theory: Be sure to double-check the pesky but hidden vacuum tube on the under side of the intake manifold. It gets lots of heat from the engine, so the rubber tends to crack over time, especially at the nipple. New tubing costs a few cents and is available at any car parts store.
Do I need to remove the intake manifold to change out those pesky ones?
Jon K
10-05-2005, 11:56 AM
Do I need to remove the intake manifold to change out those pesky ones?


not if you have small hands and remove the intake boot

Check your plugs for coked-up-ness, but don't worry... Denso Iridiums are actually great plugs, us FI guys use them widely!
Interceptor
10-05-2005, 12:13 PM
not if you have small hands and remove the intake boot

Check your plugs for coked-up-ness, but don't worry... Denso Iridiums are actually great plugs, us FI guys use them widely!
Thanks for the support on the plugs! :) Jeff made me think I payed a lot for spark plugs that are crap! Sheesh... :)

I'll start the operation as soon as the rain stops - it's a friggin flood here. Most of the islands have declared a state of elemental disaster!