a lot of random events

[carVSsuv]

Well, I have been reading and searching for a while now I want to put this out to everybody and maybe some ideas or other experience can be inputed to help out as many of the old posts were never answered so I would assume the issues were resolved.

So this is whats going on with my 92 ty.

-The truck has a miss during idle at times either during warm up or anytime. It comes and goes and can be heard thru the exhaust. This is follow by a miss as i rev the engine to 3k a few times slowly but after maybe 5 or 6 revs it smoothes out and truck idles find and drives find.
-The truck has a hard time picking up the idle after it starts. What happens is the truck starts and rpms go to 1k or so and then try to return back to normal and then will struggle to hold the idle and die. This happens 4 to 5 times as I first start on cold starts. It happens less if the time between starts is short. If you wait 10 mins to turn over again it will take 2 or 3 times for the truck to get its idle (bring RPMs up with the pedal works but is a band-aide i want to rip off).
-while driving there is a hesitation off idle and goes away at different points like 1500 rpm or a little higher and sounds like a stutter or miss and then the truck smoothes out and runs fine.
-If i am cruising down the highway, it will throw a code 44 and do the limp mode for a 5 secs or so and return back to normal and the truck drives fine again.

So after a lot of reading and seeing many others change cap, rotor, wires and plugs and not having any changes I am trying to stay away from that as all mine are within 8k of being put on the truck or less for now.

I have search for vacuum leaks and found one small one by the check valve by the FPR which i change and help a lot with the code 44 and stumbles down the highway but they still happen just not as often.

I have adjust the FP from 40 to 45 PSI line off 32 to 38 psi line on and see a 2 psi fluctuation on my gauge (not oil filled or electric its a test gauge). I can say i have not notice a huge difference in the stumbling or hesitation however its so irregular that i can not say if the affect helps or not. The fuel pump was changed in the last 9k miles to a walbro and the AFPR is from RPM.

I have checked the EGR and it works. Held some vacuum on it and not bleed down. Can see it function when i rev engine and saw the same on DM. The AFRP had no fuel coming out of the top or vacuum lines. All lines are replaced with new thicker flexible lines from the previous owner (Thanks Derek). Disconnect O2 sensor truck runs worse, truck wont run with map disconnected and I can here the IAC motor when I do the diagnostic on the truck.

I have DM but the labtop I used crapped out and i need to be the USB cable for my new one then i can post some DM. I also have a WBo2 that i will put in as well to see what the truck is actually running.


I know that everybody wants to see the DM and i do to so hopefully that will be soon. But what i did notice while the computer worked was the BPV at idle was low at 1.23 and the O2 read 14.7 most all the time until i got under some boost and it would got to 10 to 12. But i dont have any data when it stumbles. The Alt volts was 14.1 when i first looked at it.


So with all this said I am looking at the follow and please let me know what you guys think!

I want to change the intake manifold and all other gaskets over it and hopefully get rid of possible vacuum leaks as i have read good outcomes from this and is seems everybody finds bad areas when they take theirs off. *Can i get these gaskets at a local parts store or only thru vendors on here?*

Clean the IAC ports and hopefully fix the idle chase

Install the WBO2 to get a idea of what is really happening with the fuel

Get the DM going again to post logs on here for you guys.

Thanks for the help and I apologize for the long post.

 

[carVSsuv]

Re: a lot of random events

a little update...

check for vacuum leaks again and found that the plunger on the EGR would cause i big rise in rpm with carb cleaner. So I replace it with new gasket and egr and didnt notice much so far.

Also went to check the timing and when i disconnected the ESC wire the timing mark that i could see in the dark was painted and at the 11-12 oclock position. I was checking it with the timing light on #1 wire and it was far away from any others. I am hoping that the balancer has not spun but the white paint on the timing mark is really clean and new probably from last owner. When i get the chance to check it again in daylight i will.

Can the balancer spinning cause some of my issues?

 

[carVSsuv]

Re: a lot of random events

Bump and maybe some response....

I received the USB DM cable and fired it up. I dont really know how to post the file but would like somebody to look at it.

First thing i notice is the truck IAT were really high. There is a johnson pump on the truck and it is hotwired. I can hear it come on everytime put the key to on and the system is full but i think i may have air bubbles as the IAT will be at 100 to 120 and then go up to 175 or 180 at cruise at 1500 rpm 45 MPH outside temp is 75 degrees. and when i slow down or come to a stop it will drop back down to 145 or less for a short period of time and go back up again. So there is probably air in the system and i need to get it out.

Next i get a lot of knock on DM at under little boost (first record that I didnt save) and it retards my timing by 4 to 8 degrees. Hoping this is caused by the IAT's being so high.

I also see 30 degrees to 33 degrees of timing while driving around and getting my hesitation or stumble. Dont know what this is all about.

My IAC is at 38 to 42 at idle and my TPS is a.67 at idle as well. The stat in the truck is stock and shows on DM as well. My vacuum seems fine but I have to be missing something.

The O2 sensor bounces around a lot from 10 to 980 ish based on how i am driving. Can somebody confirm what i should be seeing or email me a norm log of a truck to compare things to for myself.

Let me know how i can post the file on here and i will to help get some more ideas on this.

 

[dgoodhue]

Re: a lot of random events

A slight stumble at idle is common with a lot of syty's. It can be tuned out with a custom chip. What mods do you have?

So after a lot of reading and seeing many others change cap, rotor, wires and plugs and not having any changes I am trying to stay away from that as all mine are within 8k of being put on the truck or less for now.

IMO 8K miles is a lot of miles for a cap and rotor in our trucks, especially if its modified. I replace mine every 3000 miles.

 

[2500avalanche]

Re: a lot of random events

Cap and Rotor are a necessity. You will need to change it to get rid of that problem. Believe me, the $180 you will spend on Cap/Rotor/Wires/Plugs will take away any issue you have with stumble. i experienced the same on mine, and it worked. Believe me!:tup:

 

[carVSsuv]

Re: a lot of random events

Ok so i have changed the plugscap and rotor... Storm trooper has come over to check the timing with me and we were both puzzled as the timing is crazy.

So timing it to the marks on the balancer (the furthest left) the truck would barely run. Just for giggles we went to the other mark and runs better but with misses. So we were thinking balancer. Storm trooper brought his distributor over because mine looking pretty corroded. His came out of his truck that was running good and he just upgraded it.

There was a little bit a change but i felt that the balancer may still be off and just wanted to make sure that the distributor wasnt the complete cause. Found TDC and market it on the balancer.. which it was off... Well that didnt make the truck run any better. Seemed to make it run worse.

Also... my code 44 and my cruise under low throttle still causes the truck to goo limp... So the cap, rotor and plugs may have fix a very small stumble. But the big problems are still there..


anybody else any ideas.... before i look at a balancer or where to find a decent priced one?

 

[carVSsuv]

Re: a lot of random events

BTW... I have had my egr disconnect for a few days with no change. Disconnect by pulling the vacuum line and capping the line. The IAT's went way down but i dont get a code. I have read that you will get a code if the EGR is disconnected and i have not seen this.. Is this true?

 

[EcSy#2671]

Re: a lot of random events

It is possible for the balancer to be out of alinement, If you have access to another balancer check that your balancer marks match up correctly with the keyway, so you can rule that out.

 

[carVSsuv]

Re: a lot of random events

Her is my update from what has transpired -

I changed the distributor

tried to set timing.. no timing mark where there should have been so check TDC. Found it way off from the marks. So I ordered and installed the Pioneer balancer and put at TDC. truck was running better but still missing something. So I had an extra MAP sensor and swapped it out.. and BAM!!! the truck is back to what its supposed to be.

DM says nothing but good things with a little knock at 3-4 knock retard at full runs (will work on that).

I dont have the hesitation anymore, no code 44, good milage 17-20, solid idle.

So all in all the distributor was corroded on the magnet and once i changed that it ran better and the MAP was the main issue.

If anybody has any questions about everything i saw and went thru.. please ask.. be more than happy to help. :tup: