Guys,

I have about 600 miles on the fresh built motor and starting to have some idle issues. During the timing adjustment it was set to about 750. It is inconsistent at stops.

I find myself in a lot of stop and go traffic driving around the city. At a light the idle will move up and down between 800 to 1200 rpm. I'll give it a little rev but it will continue to hold around 1100 rpm for example. The next block or a few blocks later the needle will bounce between 900-1100 rpm and will continue. I try to give it a rev but that doesn't change. It might just hold over 1k and slowly move up or down and hold.

After cataloging all of this down, I drive back home (15 miles). I get to the light and everything was back to normal. Interesting. Maybe a couple of minutes later it would do its thing again. I'm going to be driving it again today and report any new issues.

What else can I check, that's easy or would I need some sophisticated stuff to figure this out?

 

Carburated? Maybe something stuck, like cable or something.

 

Hmmmmm, everything was fine today however i'm sure that will change.

I let the truck warm up for about 5 minutes and so I was fiddling with the windshield fluid button. As soon as I touched it the idle started acting up. Then it went away. I turned on the wipers (fastest setting) and the idle started to get rough. I decided to turn on the lights as well. Idled rough. Turned everything off and things went back to normal.

Everything seem fine when I was driving. I noticed the idle was as low as 600rpm and maybe as high as 900 but then settled back to 7/800ish. No struggling. No jumping around no nothing. Today was a much cooler day.

 

...........efi

 

Hi I am anew be to this site been working on pre 94 toys for 10 years

 

I was plagued with this same issue for some time and was able to solve it this weekend by taking off my Throttle Body and giving it a deep clean as well as replacing my TPS.

 

Tomorrow I'm just going to have to do that. Again, I was driving to a light, put it in neutral and coasted. It stuck at 1500 rpm. From that point on it was stuck at 1k. 1500, 1600, Yadda yadda.

There were times where I had to ride the clutch to keep it normal range. I ended up shutting down and restarting in traffic several times only to find it moving back up right when we started moving.

It was really frustrating and annoying to be revving my truck in traffic to bring the rpms down. It has been months since I had that TB off but i guess ill have to check it and give it a good cleaning.

 

Work work work





I guess I should of taken a before pic, oh well. Surface rust gone!

 

Even more likely than a dirty TB is that your TPS is bad. I would check it using a multimeter as instructed by the FSM to do. 4crawler has a great write up on it too.

 

I took off the TB and gave it a good cleaning:

before



After


Time to drive it around, however this might be the issue:


When idling, I gave it a quick pull to simulate a tap on the gas. Twice where this did not completely compress all the way down. I sprayed it with some WD40 and I'll report back later today.

 

This is what I did. I loosened that 8mm nut and increased the distance between that thing. I have no clue what it is called.

After my driving and being stuck in stop and go traffic, the truck did not idle past 1k rpm. The whole time it stayed between 8-900rpm. I think that fixed it however tomorrow will be a different day.

Fingers crossed!

 

My money is on tps adjustment. Google 4crawler and tps adjustment...

That photo is of the dashpot, which prevents backfires when you let off the gas....no effect on idle at all. His article covers that too

 

Good stuff SqWADoosh & Philbert

I went here:
http://www.4crawler.com/4x4/CheapTri....shtml#Dashpot

I'm no good at this kind of stuff but I did have an Ohm meter and a spark plug gap (thickness guage). Following the 5 tests here are my results:

#1 - 815 (FSM - 0.2 - 0.8k)
#2 - I could not get any reading (tried to get to .57mm the best I could)
#3 - I could not get any reading (tried to get to .85mm the best I could) Whats INFINITY ???
#4 - 5.2 (FSM - 3.3-10k)
#5 - 6.6 (FSM - 3-7k)

Ummmmmmm ..... no good?

 

Not true it can affect your idle if not adjusted correctly or if like BK said it is not going down all the way for whatever reason. I had to adjust mine even after replacing my TPS and cleaning my TB in order to achieve a good 800 idle.

 

Your #2 and #3 not giving you any reading (which are the ones associated with idle) makes me think further that your TPS has gone out. Another simple method for checking if it is indeed the TPS is when the high idle happens pop the hood, hop out, and lightly tap on it with a pocket knife or anything solid and if the idle drops back down it is your TPS. These are all the things that I did myself to lead me to replacing my TPS. I recommend when you do go to purchase a replacement that you get a genuine OE replacement. They can be found at LCE or Amazon. I know how frustrating this problem is as I fought it since I bought my truck back in February.

 

Sqwadoosh, you're right, now that I think more about it. If the Dp is stuck it will hold the throttle open a bit. You could just back the adjustment screw all the way off so that it's not affecting the throttle spring at all...if you don't mind backfires once in a while

Bk, "infinite" resistance means there is no connection because there is "so much resistance". If you touch the multi meter contacts together you het zero resistance because it's a direct connection, and if you hold them apart with air between them, it's infinite.

 

Yeah I believe my meter reads "0.0L" when it is infinite. Yours too?

 

I tried repeating tests #2 & #3.

If I don't use the thickness guage, I get reading for IDL - E2. Using the thickness guage I get nothing, just a "1" staring at me.

Now if I do it manually and open the TB, I'll get readings but eventually it will go back to "1".

 

The "1" means infinite. My meter does the same thing.

You need to follow the procedure on 4crawler's site to get the TPS back to giving you a reading of less than 2300 when the throttle is just barely opened. It is possible that the TPS is bad, so that you will not be able to adjust it to work, but that would be your first step.

The TPS is a circular conductive pathway. Right now yours is rotated a little too far, so that it is not making the proper connection. You just need to loosen up the mounting screws and rotate it back while looking at the multimeter reading.

Throttle Position Sensor IDL-E2 Adjustment Procedure (courtesy of Frankenyota):

Loosen both screws attaching TPS to throttle body.

Attach multi-meter to TPS terminals IDL and E2 (the bottom two terminals on the TPS).
You can use alligator clips to make this easier or use small ¼" lengths of vacuum hose to hold them on

Insert 0.85mm (22RE) or 0.77mm (3VZE) feeler gauge between throttle stop screw and throttle plate (see picture)

Move TPS body CW/CCW until ohms reading on multimeter is infinite (open)

Move the TPS body very slowly CCW until you find the end of the resistive strip, the meter will indicate <2.3Kohms of resistance

Move the TPS body extremely slowly in the CW direction until the meter goes to open/infinite again

Tighten the top TPS screw being very careful not to disturb the adjustment

Remove the feeler gauge and insert a 0.57mm (22RE) or 0.50mm (3VZE) feeler gauge

The meter should (hopefully) indicate between 0 and 2.3Kohms of resistance.

If it does tighten the bottom screw and reconnect the electrical connector.

If not go back to step 4 and try again

To check whether the adjustment was successful start the engine and insert the timing test jumper.
If the idle speed decreases audibly it is working normally.

 

You want the "1" staring at you for test #3 that is a good thing. Its test #2 that you need to work on. As the guy above stated you need to loosen the tps's fasteners so you can move it clockwise and counter-clockwise. The ˟˟˟˟ty deal with that is that unless the PO did the allen fastener switch you are going to have to do one of two things to even be able to loosen the TPS's fasteners. #1 is take off the thermostat housing or #2 is remove the TB again.