885 TR with rough idel problems

TR just arrived with rough start and idel problems. Pulled air box assem off to check adjustments. Somebody has turned every screw on this thing. The throttle plate opening linkages are completely out to lunch, and the idel stop screws have also been turned. What is the best way to start back with a base line for propper adjustment without makeing the problem worse. I want to put everything back to stock adjustment settings, but this car is so far out I fear I'm going to open a can of worms. I have never had one this far out before. But beleive it or not the car does run(not to well,but good enough the car has been driven like this most of the summer) He real complaint is the cold start in the morning. He has to put his foot into it in order to get it started. Any suggestions?

>>Somebody has turned every screw on this thing.<<

Certianly seen that more than once...{}

Tom,

best thing to do is start with manifold vacum side to side while correcting the mixture pre-cat at the test tubes. Just work both slowly until you get the settings back in the ballpark and the running condition manageble. Once you get in the ballpark it's likely you will find something wrong which led to the turning of every screw in the first place. Who knows at this point why someone was inclined to mess around, but I'd bet there is an actual problem you will need to find and solve lurking.

Regards, JRV

O.k. I got the car into the ball park. One problem I did find was the idle switch was not being closed at closed throttle. I adjusted that. But I did find one thing really odd:

I screwed both air bypass valves to there fully closed positions. I adjusted the stop screws so the car now idles at approx 800 RPM. I was trying to get the vac readings closer on the right side bank, but as I turned the stop screw, the idle would not change. The left side was very sensitive to change. I also noticed that there was more sound (tubi) comming from the right side tail pipe as opposed to the left. I adjusted the c0 mix screw abut an 1/8th of a turn,on the left air folw meter and it woke up. But I still had the problem of not getting any response from the right side stop screw adjustment. I checked for vac leaks and found none. Any ideas? Fuel pressure will be checked in the morning.

>> but as I turned the stop screw, the idle would not change. The left side was very sensitive to change.<<

the above sounds like the engine is only really running on one bank.

Tom, did you by chance pull any CO/HC readings?

Does this engine still have the O2 sensors intact? did you try unplugging them and playing with the Mixture Screws?

If the engine is only running on partial cylinders but not backfiring I would run through a plug/plug wire test next. Generally when an engine has good spark but sporadic fuel it will backfire, if the engine has poor or non-existant spark they can still seem to run fair to poor but without any backfiring thru the exhaust.

The customer didn't give any type of clues as to how this all started? Also, it's not uncommon for someone to wash the car/engine and get the O2 sensors wet, knocking them offline, of course flooding them with raw gas for months will knock them out also {}

I did check for spark..and it is definatly there(zap!) As soon as i rev the car it really responds well..lots of power. It's just at idle seems that it does most of its idleing on one bank like you said. If I just lightly tap either one of the sensor plates in the meters I can cause the engine to stall. My c0 machine is on an extended vacation right now.(out being fixed due to an EX employee). I'm going to have to take it to my friends shop tomorrow so I can see whats up. I have run into similar problems with carb multiple carb set-up, and most of the time it's an incorrecly adjusted linkage. But I don't beleive this is the problem here. You may be on to something with the o2's being "frozen". I will also check that in the morning. (damn I just insatlled those last year!!)

As for how it all started? Well he said he had fuel dumping on the left hand side of the engine. Somebody tried to compensate for this problem by leaning out the engine(!) and in the process turned every damn screw they could get thier hands on. Now that I have pertty much got it back to spec this problem does not appear to be there any more. I will probbably show up once I've got everything right. To me that could be the PDV on the side of the FD. But I won't know until the car acts-up again.
Thanks for all the help JRV! I really appreciate it!!

I don't mean to interrupt, but how does one adjust the throttle "microswitch" on the right side FD? What is it's function?

That switch is basicly an idle switch. Same Idea as on an older VW. It tells the emission computer to allow for enrichend fuel mixture when the engine is off idle. To adjust you just have to listen for a "click" when the throttle is opened, and a "click when the throttle plates are closed(against the stop screws) The switch should click at the same time as when the throttle plates begin to open. HTH

Thanks Tom, this is something I can adjust while the FDs are off the engine, I hope. What are the symptoms if this switch is not adjusted properly? Sluggish off-idle performance?

Jeff: I removed mine, before soaking the throttle casing in solvent. The throttle has a rod at the end of it, which is flat on one side. The switch will only go on one way, since it also has a flat side to recieve the rod. After all these years, the screws that hold the switch on, left a visible mark. I just placed the screws to these marks. The total adjustment is only like 1/16 of an inch. This is because that is the only movement of the slots in the switch bracket, that hold the screws to attach the switch to the casing.

I will verify what Tom states by using an Ohm meter to measure the resistance in the switch, while moving the throttle.

Sorry about the late post....(girl friend called)
The switch is just an on and off signal. You can easily check it for continuity by just probeing the terminals on the switch with a multi meter and working the throttle. (difficult to do on the car but since you have yours off it can be done easily).

As far as symptoms of an inoperative switch..you can have difficult cold starts a sugering idle and high HC readings for emissions. I have yet see one fail..but I have seen one miss adjusted(see above) Not because somebody loosened the switch off and tired to move it, but because somebody was playing with the idle screws and opened the throttle plate too much thus causeing the switch to now be out of adjustment.