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Thinking of doing the unthinkable... *Rotor to cap gap. Normal?*

Ok guys, good advice. Ive looked at that distributer for cracks before and saw nothing. Ofcoarse that thing does have 215k miles(as far as i know). I think im going to actually put a new IAC (ive cleaned it but as i understand it can still be messed up) and a new ignition module. Maybey pull the dist out and inspect it first. Depending on how much the dist is i may just get a new one as i think it would come with the ignition module.

k5greek91, I dont know why i didnt take your original post to heart but i guess i just thought that a bad ignition module would "show its face" a little more blatently(sp?) you know?

P.S. You better belive i'll post up when i finally fix the problem!
 
yea i know what your saying.. but look at it this way.. your truck is probably gonna come out of this running at 100%:D
 
When you were looking for vacuum leaks, did you try pulling the line/valve out of the brake booster,and capping it off?? My 90 Suburban had a funky idle problem a year or two back....checked everything I could think of, check valve on booster was fine, and I was pretty sure the booster itself was o.k..
Couldn't find the leak, and it wasn't until a month or two later (when my brakes started feeling funny) that I figured it out. Booster was fine. Not too long after, I started feeling it in the brakes, the idle would get real bad while the brakes were applied, and at that point I could hear the leak. Still thought my booster was shot, but turned out the rubber/neoprene donut gasket between the booster and master cyl., had degraded, and became deformed.
Air was being pulled from between the brake master and booster, around the pushrod, and into the booster...
Even before having any other symptoms, this caused my idle to be rough and eratic. All I replaced was the check valve on the booster, and the donut between the brake master and booster (couldn't find one/ had to take off another booster)...Idle problem fixed and running perfect for at least a year now.
This probably won't help you, but what the heck...can't hurt to check right?
Good luck with it.
 
I will deffinetly check that then to as well. I got a new ignition module last night and it didnt change anything either. I think im going to try to find a new distributer at a wrecking yard, and get a new IAC and see what that does. As far as the EGR i had a brand new one on there that seemed just fine and just for grins i put my old one cak on and it didnt change how it ran at all either.
 
i have a similar problem on my 90 blazer, but without the surging. the last few months it just runs kind of rough and you can really tell it when idling, the whole truck kind of shudders and shivers. but this forum has alerted me to some things that i should look at to narrow down my problem. i am new to this forum and have been reading articles for the last 2 days straight, it's just the first step to getting my truck back to "scalded ass ape" status (i rofl'd when i read that phrase) and i hope y5mgisi gets this figured out without dumping too much $$ into it.
 
Please, please post your solution to the problem. I have a very similar problem.

Good luck
 
I ended up putting a new distributer in and a new iac also and still runs the same as ever. So now i am 100% completely fed up and cant take it anymore. I swore i would never convert this truck to carb because i love the TBI so much but what else can i do you know? It just pisses me off that i have rebuilt several trannys (auto and standard) several motors, all kind of stuf like that but i cant figure out a ****ing idle problem.
 
Have to admit I haven't read every reply but did you check the IAC passage? They carbon up. Is it doing it in drive as well as N & P? If not, what about the P/N signal switch to the ecu?
 
y5mgisi said:
I ended up putting a new distributer in and a new iac also and still runs the same as ever. So now i am 100% completely fed up and cant take it anymore. I swore i would never convert this truck to carb because i love the TBI so much but what else can i do you know? It just pisses me off that i have rebuilt several trannys (auto and standard) several motors, all kind of stuf like that but i cant figure out a ****ing idle problem.
Click to expand...

Ive read most of the thread, did you try taking it to a shop????
 
79k20350 said:
Ive read most of the thread, did you try taking it to a shop????
Click to expand...

I agree. I'd suck in my pride and take it to a reputable shop before I went carb at this stage in the game. :confused: Man I'd love to have fuel injection on my ride.

I subscribed to this thread when it was first posted because I wanted to see what the problem was in the end. You can't do this to us! We want to know what the problem is! :mad: :D

But seriously, good luck in whatever you decide...:)
 
I had a similar problem with my old K-5. Turned out to be the new plug wires I'd put on. Aparently 2 of them had some issues. I never thought to check because they were new.
 
A surging issue caused by plug wires? Im not calling BS but just dosnt seam like that would cause my surging issue. I think the big thing with a shop for me is that most shops are around $60 an hour labor rate. I could just see them messin around with it for 5 hours and still not fixing the problem.

And about the IAC Yes i cleaned the passages and ectually ended up having the whole throttle body rebuilt with no difference.

About the P N switch, In park or neutral it just sorta runs rougher than it ought to. but in drive is when it makes it self more noticeable.

I pulled all the plugs yesterday and they all look pretty good. have a nice slight chocolate color to them. Also did a compression test and all are at 130 give or take 5 lbs.

It SEAMS like it is getting too much fuel at idle. When i look down in the throught of the TB i can see the fuel sortof building up and splashing all over the place. however, at no point will it blow black smoke...
 
im sure u checked the fuel pump but on my dads 95 454 tbi the way u discribe the fuel splashing is exactly what was wrong with his and put a new pump in and it was still there but come to find out the new pump was bad also so got another and then was fine.
 
I would take another look at the Dizzy and TB itself.

Was the TB rebored, etc? Are you absolutely sure it was done correctly and any/all air leaks were fixed? Was the slop removed from the throttle shaft? Did you put a new IAC in or just clean it?

Those Distributors are notorious for failure. I would not use a used one, but at the least verify that it worked right beforehand and check it out really well. I don't think they are outrageously expensive from GM.

I have had problems with Ignition, Fuel delivery, and the ECM on my TBI trucks.

That cam is plenty mild enough.
 
Thanks for the reply. To answer your questions, The TB was not bored oversize, however the throttle shat was bored to accomidate new brass bushings(this was done by a very profesional/experinced shop). The same shop alsocompletely rebuilt and flow tested my injectors/FPR etc. I first cleaned the IAC but was not convinced it was good still so i got a new one and put it in. The distributer was a rebuilt unit from a-1 cardone. All of this resulted in no difference in the way the truck runs. Basicly the onl thing i have not replaced is the ECM itself.
 
i have a buddy, who owns a 91 2500 4x4 burb, & his truck was doing exactly like you are saying yours is doing. we went thru everything, replacing o2,tps,etc,etc..when it was running at idle, you could look down the tb and 1 injector wasn't spraying a cone of gas like the other, so we replaced the injectors, still the same problem, 1 injector dribbling gas in drops, we thought maybe fuel pump going out, we had a friend who has access to all the tools needed, come by and test the fuel pressure, it checked out ok.

after we had replaced everything we could imagine from all the sensors,tps,o2,ign mod,etc,etc....we went to our local gm dealership to talk to a tech,..1 of them took a break and came outside to talk w/ us and listened to the truck and started naming stuff it could be, we were like yep, that's new, that's new also...everything he mentioned we had already done it or replaced the part, then he asks us if we had changed the temp sensor, which we hadn't b/c we didn't think it would effect idle, he said it could be sending the ecm the wrong info, like telling it that its 300*(leaning out) and then rapidly swing in telling the ecm it was 30* below(getting rich) and the ecm would try to work w/ the info it was being sent, thus causing the problem. the dripping injector is what made him ask, b/c he said it was flooding BAD and thats was why the injector was dripping instead of spraying...which made him think temp sensor could be malfunctioning...

we stopped at advanced auto on the way home and picked up a stock temp sending unit for his 91 burb. when we got home we replaced the sending unit, and the problem went away, the injectors were spraying the cone shape and it ran better than it ever had run(possibly b/c everything replaceable had been replaced)...the truck still runs good to this day! you'd think you would be able to see this w/ a scanner, but you said it never acted up & idled erratic when hooked up to a scanner, so it could possibly be the temp sending unit sending the ecm wildly changing info. and the ecm trying to run w/ bad info being sent to it!
 



as mentioned above with my holly projection unit mine would run erratic at times, stall out, 1 injector chose to be an odd ball even after swapping a new on in its place.. would flood too

The set up ended up on my friends truck, result was the temp sensor
 
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