Idle adjust

[Bob Beauchaine]

I've got a slight problem - I can't adjust the idle on my '93. I've turned the idle adjust screw until it sits about 1/8 of an inch from its throttle stop and I am currently running 850 to 900 rpm at idle. This happened after I turned up the power screw. I've cleaned and checked the pump linkage and the throttle linkage all are OK. I've also disconnected cleaned and checked the throttle ball sockets and checked the length - also OK. I will install a new power screw tomorrow that will allow for more adjustment so the idle will be going up once again.



Anybody got any suggestions



Bob

 

[formula]

Well, couple of things come to mind from what I've tweaked around with. First, if you crank the fuel screw way in, it will begin to override the governor and the idle screw will have no effect at all. If this is the case, be careful because more turning of the fuel screw can result in a runaway. Secondly, you may need to tweak around again with the length of the linkage. If you set it to factory specs it will be too short. To allow for the proper travel, I had to set mine almost to the end of the threads.



Cheers,

Sean

 

[hdm48]

Bob, Formula is right about the linkage, check it. Also, I found I needed to lengthen the notch for the TPS ( in the metal mount) so it will travel further. But then you get to play with it's adjustment.

I hope this helps.



Dave

 

[CDegner]

Dave,

I ran into the same problem you are talking about with the TPS. I could not get my idle down no matter what. Turned out it was the TPS keeping it from returning to the idle set screw. A few adjustments and all was back to normal ... whatever that is.



I doubt that is Bob's problem though. He has a NV4500 so he does not have the TPS. Lucky him!! The linkage or power screw setting are the likely culprit in this case.



Carl

 

[Bob Beauchaine]

I will look at the linkage again to see if I can do anything with it. As far as the power screw goes I still have 1/4 to 3/8 of an inch of threads left and I am currently running about 27 psi of boost @ 3000 rpms.

Bob

 

[formula]

Do you mean that there are 1/4 to 3/8 inch of threads left on the screw AFTER removal of the lock collar? If so, that's getting up there pretty good. However, it's a bit difficult to tell how far the screw actually is turned in because the adjustments vary from pump to pump. One thing to definitely watch out for is that when you're turning in the screw it will reach a point where it suddenly becomes much more difficult to turn. It's at this point that the governor will begin to do strange and unusual things.



Sean

 

[Bob Beauchaine]

I replaced the old Power screw with a used but good one from a local Bosch rebuilder. It still had the collar on it so I removed it and cleaned up the threads. I then pulled the one on my pump and took a good look at it. The lock nut was right up against the spot weld used to hold the original collar in place. There was no collar on the original so in effect I was against the collar. The original was pretty "screwed" up but repairable.



I also went all over the linkage and triple checked everything - still a nice 900 rpm's.



Bob

 

[formula]

Did you completely remove the threaded rod from the balljoint linkage and try running the engine that way? I'd highly recommend that you try it. That will let you know if you need to look further into the pump or make further adjustments to the linkages. The balljoint linkage also may not be the culprit. Check the lever where the throttle cable attches and check the cruise control cable and throttle cable to make sure nothing is binding up there.



Sean

 

[therabbittree]

i have the same problem i just dealt with mopar for the last 2 weeks getting a replacement rod and ball ends. . argh. . any how mine either doesn't get full throttle or doesen't get to idle. . argh its getting old quick. . i wish we could just have a cable throttle with out the linkage. . anytips on how to achieve both idle and full throttle? i have my power screw turned in a bit but it still idles without the linkage on etc. . later

Deo

\x/ hillfolk!

 

[BushWakr - RIP]

I'll be interested to see how this one resolves itself... . for the moment, I'd be wondering if the total "fuel screw" adjustment has just plain taken the pump/linkage out of adjustment range.

The only way I can think of to remedy this is either to ease back the full fuel screw, OR, live with the higher idle. That's not a good choice if you're driving an auto though... .



Aside from that the next stage would be to look at the indexing of the throttle shaft. Now I'm pretty sure that you will have other headaches if go that road. .

In my case I found that the threaded rod was too short if I went too far with the fuel screw, until I put the gov spring in...

The full fuel screw has a natural limitation based on it's length and also on the movement range of the compound lever(s) if contacts internally. So basically you've probably gotten as much as you safely can from the pump. Keep in mind that some pumps are just subborn and others love to be opened up more and more... . well, sort of... eh mark. .

You are likely so close to runaway that you asking for trouble.



bob.

 

[rowland]

me too

Just for the record I have exactly the same problem. Even with the throttle linkage removed it idled too high with 1. 5 turns on the fuel screw. I ended up backing off the screw a little and using the fuel pin too get the fuel I needed. Now thats maxed out too and I'm getting 19 psi. The problem started when I changed the head and injectors to '93 style. With the original '89 equipment it ran 29 psi and idled fine. If anybody figures it out let me know.



To get full throttle travel I lengthened the linkage and then shortened the cable using spacers at the pedal. Results in increased throttle travel. Worked for me, may not work for you.



Good luck.



Isaac

 

[Bob Beauchaine]

I have run the pump without the ball sockets being hooked up. Pump totally disconnected from the throttle - makes no difference.



For the record this "built" pump probably has governor springs already in - it has always maxed out at 3000 rpm's. In addition the idle ran at 800 to 850 - since May of 2000 when it was installed. The main reason I posted was to see if anyone had any ideas about lowering it since the idle screw will not work. When I bumped the power screw up I did not think that I would not be able to adjust the idle. I have run it against the adjustable full throttle stop - so far no runaway.



I can usually come up with these kind of "stumpers" and I do appreciate all the input. Someone has the answer and I will continue to tinker in an effort to find an answer.



Thanks again

Bob

 

[formula]

To clarify... ... . the "runaway" that we've been talking about is not excessive rpm when you advance the throttle lever to WOT. It will occur with the throttle at idle position. As soon as you start the engine, off it goes. In that case, hopefully the shutoff solenoid will kill it. If not you'll have to back out the fuel screw, use the shutoff lever or choke the air supply.



Now we know that the problem lies within the pump and not the associated linkages. Can you manually pull back the throttle lever on the pump to achieve an acceptable idle speed? You mention max rpm of 3000. Is this no-load rpm WOT in neutral? Or does the pump begin to defuel at 3000rpm? FWIW, mine runs a max no-load rpm of about 3100 and begins to defuel at about 2700rpm. It does not have a gov spring change and there are no internal modifications.



Deo,

There is a bit of grinding that you can do on the bracket where the throttle cable attaches to the lever. Grind off the top of the C-shaped notch so the tab on the lever doesn't hit it when on WOT. That way you can crank up the high idle and be able to use it too, without loss of low idle control. Since you've got an auto trans, check the TV cable to the trans. If you crank out the high idle screw you'll have to slack off on the TV cable to allow for the extra travel.



Oh..... and there is also the trick of bending back the go-pedal so it doesn't hit the dang floor mat



Cheers,

Sean

 

[BushWakr - RIP]

Sean,



Just to clarify on the one point you made re: runaway.....



It can occur right at startup if you've advanced the screw too far, OR, it can lay in wait for you. This test is one that nascar mark suggested and I've seen the "signs" he mentioned.

After startup, blip the throttle a few times, and wait to see what happens... . If the idle drops back promptly to normal levels great... but if it hangs for a second or two, or doesn't seem to want to come back down, then you're on the verge of a hellatious foot race to get the fuel/air shut off... .



In fact there was a recall on the runaway condition that most of you know about. That runaway condition could occur under both conditions I mention above.



Bob.

 

[formula]

Ah crap..... you're too fast Bob I was just editing my previous post on that matter



Sean

 

[dpuckett]

Rowland,



I looked at the injectors in my 91 today after taking them out to replace the head gasket, and the holes in them are HUGE compaared to the 91-93 injectors I was used to seeing. The PWs flow less than the stock 9mm tip injectors.



Bob Beauchaine,



How many threads are showing on your power screw? Mine is turned in more than I ever would have gone on my own. Collar still on it; but looks to have been turned in 2. 5-3 turns past wher it first hit. So that would make 5 threads left (since the two screws I removed [for collar removal] had 8 threads where the collar started). I havent messed with that one yet. WOnt till I get a intercooler. Hit 1300 here at sea level after a long climb.

 

[Bob Beauchaine]

OK It passes the Nascar Mark throttle "blip" test - comes right back to idle. I tried it several times as in seperate times and will try again when it's hot.



It starts to defuel at the same approximate spot as it always has - about 2900. When I put in the DD3+ injectors it doesn't start to defuel until about 70 mph - roughly 2900 rpm's. With the PW's you could feel the lack of power at about 65 but it would still accelerate to 70 - just a whole different feel.



You can't make the idle drop by pushing against the linkage even with the space between the set screw and throttle at 1/8 of an inch.



Right now the power screw is less than 1/2 of a turn past where the collar would have stopped it. It's going to stay there until I find an answer.



Bob

 

[JStraw]

I posted a while back about having the exact same problem. And still have it. I seriously believe the problem to be internal but don't have the down time required to bust it open and see. I do have a question, can the TPS be removed from its bracket but still be electrically hooked up, then with the motor started be manually adjusted to see if it makes a difference?



Mine started when I removed the lock collar and turned the screw in one turn and no matter what I've done since it remains high. For the longest time I thought I was the only one to have this fluke but with it occuring to more of us, has me thinking its a related part wear problem.

 

[JStraw]

TTT

Has anyone come up with anything on this problem?

 

[Bob Beauchaine]

Not yet - it still runs at 900 to 950. I am beginning to think that the only way to drop the idle is by re-indexing the pump. It runs so well now that until I hear of another way of attacking the problem I'll just run it the way it is.