engine and drivetrain Engine Idles at 2000rpm and exhaust pops on decel

[avoirdupois]

Pardon me for typing this, and I don't mean to dampen your enthusiasm, but you might find it more advantageous if you stayed with one thread when dealing with the same subject matter. I have not taken the time to view all of your recent posts, but this one (  http://www.bmw2002faq.com/topic/177159-re-tuning-after-smog-check/   ) to which I had planned leaving a response, sure seems to cover some of the same ground as this current thread.  Keep in mind that if you want responses to consider all cumulative information, one thread helps you and those who respond.

 

Many of your questions have been discussed several times over on this board, so you might start with reading through the owner's manual (available elsewhere on this board)  as well as any basic shop manual, for basic maintenance procedures that apply to most cars, let alone the car you just started driving. I will not harp on searching the archives, but it couldn't hurt. 

 

BTW, plugging vacuum hoses is intuitive.  In addition to suggestions made in response to your post on the subject  http://www.bmw2002faq.com/topic/177374-best-way-to-plug-vacuum-lines/  , a common BB in a short line of hose works pretty well.

Edited February 19, 2016 by avoirdupois

[silasmoon]

Thank you very very much Mark, I will get to that today or tomorrow morning pronto and report back. 

As far as multiple threads, I would agree that perhaps I should've kept things under one topic. As for searching the archives, believe me I have read just about every single thread on here regarding pop on decel, idle times, setting timing, weber 32/36's, the weber manual, and Mike Macartney's book even. I am - however - a very visual learner. You might notice a lot of my posts include tons of photos, and I would hope that other new 2002 owners might find those photos useful. Archived threads often are filled with posts only stating n/t or broken links. They are fragments in the wind and often have a lot of conflicting information. I have to say this is one of the best user forums in terms of getting questions answered I've ever encountered. Really people on here are immensely helpful. It's almost too tempting sometimes to whip up a new thread. With that said I will try my hardest to not start "How do I tune?" threads, use search, and always try to provide relevant information with as many specific details as I can muster. If only I could share my search history

Thanks! 

 

[avoirdupois]

 

As far as multiple threads, I would agree that perhaps I should've kept things under one topic.

 

 

 

I do understand your conundrum.  When in doubt, you might consider simply listing or  linking any semi-related post/thread, so everything can be viewed in context.

Edited February 20, 2016 by avoirdupois

[silasmoon]

Status report -

• I backed out the idle speed screw out, then once it touched the brass lever I gave it another 1.5 turns in.
• I then finger tightened the mixture screw until I couldn't tighten it more with light force (this is how I understood lightly seating) then backed it out 2 turns. 
• The car wouldn't idle at all in this setting or with adjustments to the mixture screw.
• We then reset the mixture screw to baseline, and gave the speed screw another 1 turn so it would idle roughly.
• We then calibrated the mixture screw, which ended up being about 1.75 turns in so it idled smoothly at about 200 rpms.
• We then turned the idle speed screw 2-3 times until we got it to idle at 900 rpms. 

The car needs to have a valve adjustment, new spark-plugs, re-timed and the throttle linkage likely has slop. I am open to further suggestions of jetting, but didn't want to take the carb apart just yet.

[Stevenc22]

http://www.bmw2002faq.com/_/technical-articles/engine-and-drivetrain/weber-3236-jetting-prescription-r22

 

I have a digital AF meter and have been working on my tune for a couple months now. Every time i changed one thing i made something else worse. In the end i gave up and put in CD's recommended jet sizes and AF is generally excellent.

 

I highly recommend CD's jetting perscription as a good baseline!

 

You will need to buy various jets of various sizes (Sizes that don't come in kits)

 

I bought mine from Pegasus racing.

 

https://www.pegasusautoracing.com/group.asp?GroupID=WEBERDGVJ

Edited February 22, 2016 by Stevenc22

[avoirdupois]

Status report -

• I backed out the idle speed screw out, then once it touched the brass lever I gave it another 1.5 turns in.
• I then finger tightened the mixture screw until I couldn't tighten it more with light force (this is how I understood lightly seating) then backed it out 2 turns. 
• The car wouldn't idle at all in this setting or with adjustments to the mixture screw.
• We then reset the mixture screw to baseline, and gave the speed screw another 1 turn so it would idle roughly.
• We then calibrated the mixture screw, which ended up being about 1.75 turns in so it idled smoothly at about 200 rpms.
• We then turned the idle speed screw 2-3 times until we got it to idle at 900 rpms. 

The car needs to have a valve adjustment, new spark-plugs, re-timed and the throttle linkage likely has slop. I am open to further suggestions of jetting, but didn't want to take the carb apart just yet.

 

 

A carburetor is like a box of chocolates.  You never know what you are gonna get.

 

Your carburetor is versatile in that it can be adapted to fit numerous engines, none of which share exactly the same fuel requirements. For decent engine operation, you need proper jetting.  Wrong jets generally render other ignition workarounds an exercise in futility. The silver lining is that you are probably not far off base since you have been able to drive the car. Additionally, one of the easiest things to do is check and, if necessary, replace, the primary idle jet that is accessible from the side of the carburetor. I wouldn't be surprised if you have a "50" jet and could eliminate many of your lean driveabilty problems by going up one or two steps - to a "60." But this is idle speculation on my part, especially if you have not done equally rudimentary maintenance such as checking ignition timing and valve adjustment.

[Mark92131]

A carburetor is like a box of chocolates.  You never know what you are gonna get.

 

Your carburetor is versatile in that it can be adapted to fit numerous engines, none of which share exactly the same fuel requirements. For decent engine operation, you need proper jetting.  Wrong jets generally render other ignition workarounds an exercise in futility. The silver lining is that you are probably not far off base since you have been able to drive the car. Additionally, one of the easiest things to do is check and, if necessary, replace, the primary idle jet that is accessible from the side of the carburetor. I wouldn't be surprised if you have a "50" jet and could eliminate many of your lean driveabilty problems by going up one or two steps - to a "60." But this is idle speculation on my part, especially if you have not done equally rudimentary maintenance such as checking ignition timing and valve adjustment.

 

Your primary idle jet maybe too small based on your current settings, you can check it without taking the carb apart, it sits behind the brass screw holder in the attached picture.  Unscrew it and use a magnifier to check the current jet, then go to Pierce Manifold and order 2 sizes up, or 2 jets in single increments up.  Current .50, next .55 and .60.  Replace the current with the next size up and repeat the best idle instructions.  Ideally, you are looking for 1 to 1.5 turns out on the idle mixture screw and 1.75 to 2.0 turns in on the idle adjustment screw.

 

Have fun...

 

Mark92131

[silasmoon]

Alright I got a idle 60, main 140 and air correction 145 based on this guide. I am 90% sure I have a 50 main jet currently. Before I fuss with that though I am going to do all the other basic care. 

Edited February 23, 2016 by silasmoon

[lloyd]

Two things catch my attention in this photo.

 

First, I glimpse part of the upper carb gasket (bottom left), suggesting the possibility that it is backwards or improperly installed. This could provide ample reason to remove the top of the carburetor to catalog jets.

 

The second observation concerns the device used to adapt the carburetor to the original Solex air cleaner. I do not recall ever seeing any air flow numbers with the adapter installed. (I am not sure why anyone would have those numbers unless they were trying to sell an adapter.) Still, it does not take a Brain Surgeon (or VP Candidate) to conclude the device must negatively impact air flow at WOT. Maybe two chokes are one too many?

 

 

 

 

 

There may be an improved adapter that does not choke WOT-flow as much as the prior example.  Although it is unclear how this would easily accommodate the original filter housing.

 

 

 

Modification of the filter housing seems the least air-flow-restrictive method of retaining the original look and filter.

 

 

Edited February 23, 2016 by lloyd

[silasmoon]

Interesting on both counts for sure. I didn't assemble the thing, I'm just hunting. I've heard the original air filter with its snorkel is pretty great actually, I'd like to keep it. Are there any aftermarket adapters that don't require modifying the original filter?

[Stevenc22]

My car originally came with the same adapter you have. While it might be slightly restrictive, it isnt the reason for your current problem. First things first

 

 

I would immediately go in and change the jets to recommended jets in the article. That is a proven safe if not rich prescription. Then if the car isn't running right, you know its likely not the jets. When chasing an unknown problem, try to eliminate things one at a time rather then fixing 10 things simultaneously.

Edited February 23, 2016 by Stevenc22

[silasmoon]

Yeah you make a good point for sure. I think my little laundry list of fixes is just always growing - I doubt the little coverage amounts to much HP loss in general. At least no more than the girlfriend sitting next to me.

[silasmoon]

Finally got around to doing general maintenance:

• Replaced and gaped spark-plugs to .40 with platinum plugs (I know, I know I ordered new BP6ES, but Autozone goofed). 
• Measured compression and it was 150 / 148 / 150 / 148
• Adjusted the valves to .006 intake and .008 exhaust. Also used a fancy engine turn bar we had at the garage - made it super simple.
• Timing sounded good, and car runs fine, so we didn't touch it. 

A few thoughts:

• Measured resistance from distributor cap to spark plug ends and each was about 1000 ohms. 
• Engine sort of "ticks" now, which I've read is actually a good thing. Most of the exhaust valves were tighter than .006, so its a new noise for me. 
• Tightened that nut that holds the oil distributor over the cams.
• Engine now wants to idle at 1100, so I have to adjust that again. 
• I couldn't for the life of me see that ball anywhere in the viewing window. We stuck a pencil eraser down the hole to clean it, but no cigar. Suggestions? 

['76mintgrün'02]

Put the car in fourth gear, take a bright flashlight and slowly roll the car forward while watching for the BB.  When you find it, paint it white.  I dipped a bamboo skewer in paint, then touched it to the BB.  I then drew a line as well, to make it even easier to spot, because the BB is sort of far forward on the flywheel and the angle of sight sucks.

[Stevenc22]

The BB is positioned at the front of the tranmission hole and since you generally look "backwards" when looking into the transmission hole, you can easily miss it completely.

 

Try to look vertically straight down into the hole and you will find it.