93Euphoria

So Ive been chasing this problem for the past year or so and she just wants to be difficult. Few months ago I took your guys advice, got some Dielectric grease and rubbed a good amount on the ICM plates, between the head & the plate, under the coil, even on the bolts because of how this car is giving me OCD Turned out that didnt do anything. So I decided to give it a rest because of work and recently had some free time to worry about the issue again. Havent tried the O2 sensors yet, but this hesitation problem didnt occur until I replaced the coil to an MSD. So im convinced its either the coil or ICM. It could be O2 coincidently going bad. The shop where my old man (The Tire Choice) doesnt have any OBD1 tools to check for codes. I hate for anyone to spoon feed me anything, but any knowledge on what moves to make besides O2 sensors will be appreciated. I dont want to replace what isnt broken.

Note: Incase anyone isnt familiar with my threads on this 1 issue- Only hesitates, Mis-fire feel, when its at its normal operating temp range. She runs like a champ for 10 mins after a cold start-up. She’ll start to bitch once the electronics, coolant gets to 180. At idle at a stop light the RPM’s will drop for a split second then back to normal, then back and forth.... No SES light, has new wires, plugs, and fairly new Opti. Everyone is so quick to jump to a conclusion to blame the opti..

ugod02010

sounds like what my 94 is doing. I got a new icm today and stuck the stock coil back in and it hasn't helped. pain in the ***.

93Euphoria

Yes it is a pain in the ***. Ive tried everything from Wires, Opti, Plugs, New MSD coil(it got worse with the new coil. Old coil I made the mistake of giving it to a friend), Fuel Filter, Cleaning MAF(93 Z28 with 94 computer), Dielectric grease the whole car. Only thing left on the list is O2’s, ICM, IAC. I just dont want to buy something that isnt broken. Most of the guys I took it to (which their knowledge on LT motors arent as good as the guys on here) said it was the opti. I explained the Opti was relatively new and most still blamed the Opti. lol Even if it is im not about to go down $400 within 1 year.

The hesitation occurs when you give it between 20%-40% throttle(depending on speed) Occur more often in stop & go traffic. You give it more then that, then the converter kicks in and the hesitation stops in higher rpm. Only does this when the motor is warm. Its kind of a pain when your hotrodding with friends, and your friends shitting GT, Challengers are able to accell with no problem and the only way not to dumb down the process is to give it near full throttle. Lol

Other then that she runs fine anything above 2800RPM. She has a minor hiccup at 4K then again at 5k (pretty sure its a fuel problem), but thats another problem for another day.

Ed Wright

iTrader: (1)

Could be a dirty/dead spot the wiper in the TPS passes over if it actually is at the same throttle angle every time.

With no OBD1 scanner, how do you actually know the % throttle angle?

If you are going to just throw parts at it, may as well throw a TPS at it next.

If you have a laptop, Datamaster and a cable might be a good investment. You would need the "EE" version.

duh

iTrader: (16)

This is darn near the same problem myself and a few other guys are having. I have a datamaster log I posted hoping someone could see something I didn't. My tps was fine, but BLM's show red. New o2's on mine, car has what seems like a miss at idle and around 2500-3000 rpm with a hiccup at 4000 under WOT. I've done the map and iat sensors, just to be on the safe side. It's run identically with 2 different opti's and another 2 were DOA. I'm waiting on a forth to show up under the warranty. No engine light to give a clue where to look. The only difference with me is the Delteq setup. Plugs looked a bit lean, but it was expected with the BLM's where they are. Once the next opti shows up, hopefully I can give some answers. Hopefully.

93Euphoria

Yeah as far as the % was just a rough estimate with my foot. Does the same % every time.

How exactly do you check the TPS spot? I disconnected the TPS, unbolted it from the TB and see if I could understand what you were trying say and it was clean. Maybe im missing what the wiper is exactly.

Unfortunately I dont have a laptop. So ill have to buy a cheap use windows one.

93Euphoria

It sounds like were all in the same boat.

Haha id like to see your datamaster chart so I know what im looking at when I start getting into tuning and all that computer stuff. I kinda been doing research on the coil, reading all the testimonials of how MSD’s are worse then Stockers, A/C Delco’s, Delphis. Oh-well ill let the coil rest and throw parts at it to an extent.

My only concern is if I should waste my money either on 3 things: GM dealership, Throwing parts, or Window laptop with Datamaster.

Been checking the car up and down religiously and every connecter, hose, fitting, appears ok.

duh

iTrader: (16)

Well......I finally got another new opti. This one was brand new, even a freshly machined base. Unfortunately it's still doing the same thing, a little less though. I actually had a great log of it going for a nice little drive. Then the car even quit acting funny! Figured "great I've got a log of what it was doing and then when it stopped all in one!", only to find out it didn't record! I'm going to have to Log and drive some more and see what happens. I keep seeing a bunch of things happening at once, and I thought I'd be able to look t it and figure it out, but I was mistaken. Good news is I don't think it's OPTI related anymore, as I find it hard that 3 would do the exact same thing. Maybe I can hook up with Ion and see if we can't figure this thing out.

NewOrleansLT1

I hate to say it but it sounds like your o2's, but you can also check your plug wires for burnt spots also

jaycenk

iTrader: (1)

TPS test is easy for anyone with a multi-meter and some knowledge on how to use it. Simply test for voltage with the key in the run position but the engine NOT RUNNING.
Check out shbox.com I think he has the test on there or check the web. One of the 3 wires going to the TPS will have between .5 and 5 volts on it between closed throttle position and wide open throttle position. If you loose power during a slow sweep from closed to wide open throttle or do not get close to the .5 closed and 5 volts wide open throttle then its a bad tps. If you get 4.5 at WOT that's still ok and if it reads .3 at closed this is still ok but if it only reads like 2 or 3volts at WOT(wide open Throttle) then there is a problem. It should slowly increase as you move the throttle from closed to wide open. If it starts to loose voltage at any time while advancing the throttle then you need to replace the tps.

Another question for the OP you said it runs fine for 10 min until it reaches temp but you live straight across the state from me and it should not take that long to warm up. Mine reaches closed loop in about 4 or 5min driving from my neighborhood to main road which is about 4 miles at 30mph. Have you checked the thermostat? If it gets stuck open it could be too cold and causing some problems. Also you said you put dialectric grease between the head and the heat sink for the ICM?? If you did you need to get that out of there and add a couple of washers to space it off the head so the head does not heat soak it.

duh

iTrader: (16)

I can't speak for the OP, but my car has brand new delco o2's in it. And according to the histogram on datamaster, my ECM is doing nothing but pulling fuel. I've got an email into Ion to try and get together and see what's going on.

duh

iTrader: (16)

After a lengthy chat with Ion, its come down to a possible ECM issue. Now just gotta find one to test it.

93Euphoria

Thanks ill check that out ASAP

Another question for the OP you said it runs fine for 10 min until it reaches temp but you live straight across the state from me and it should not take that long to warm up. Mine reaches closed loop in about 4 or 5min driving from my neighborhood to main road which is about 4 miles at 30mph. Have you checked the thermostat? If it gets stuck open it could be too cold and causing some problems. Also you said you put dialectric grease between the head and the heat sink for the ICM?? If you did you need to get that out of there and add a couple of washers to space it off the head so the head does not heat soak it.[/QUOTE]

Yes it runs fine for about 10 minutes of driving until the problem occurs. Now if I let the motor warm up and let it sit at idle after a cold start up for about 5 mins, then I drive, that is when it’ll hesitate on acceleration (Assuming that the engine gets hotter quicker when it idles after cold start up). I guess it has to do with the open loop, close loop PCM thing. Ill have to do research on how the Loops work. Ill drive it on the highway for about an hour++, get off an exit, stop at a light and it’ll get so bad the car sounds like its running on 3 cylinders when acceleration, but then once its cruising & accelerating 70+mph she runs fine.

Ill wipe off the grease off between the head & plate. Add washers & swap out to Delphi O2’s.


The thermostat is a 160 degree one. Got it over a year & half ago and it helped keep down the temps.

93Euphoria

Nope fortunately no burnt spots on the wires. Ask me why. It only took me 24 hours to replace all 8 of them.

93Euphoria

hey guys. Update,

Got 8 spacers from lowes and the hesitation simmer down a little bit. I didnt drive her long enough to really push the test effectively to see how well it fully worked. Only drove it 15 mins(From my house 5 stop lights= 3 miles till I-95. Then only 2 miles=2 exits, then 3 miles of city driving to where I work), but it helped some what. It use to hesitate on throttle consistently until either I let go of the throttle or it shifted into high gear/rpm. With the spacers it hesitates only in a bipolar fashion upon the same situation. Its a pain just trying to explain it lol. To fully see how well it worked im going to have to drive down to Homestead to pick up something later this week. As ive stated before the Hesitation gets worse when you cruise on the highway for longer then 30 mins. Which is something I dont understand myself because after driving long distances on the highway the front end of the motor & motor cools down (coil, icm, intake elbow, ect) All of the above gets hotter in city driving. This is where my car is screwing with my head.

Aside from that I didnt want to post this other recent problem just yet because:
1. its an on & off issue
2. I wanted to deal with 1 issue at a time.

Ill make another thread about the A/c issue im having with hot air some days & cold air other days.

jaycenk

iTrader: (1)

If spacing the ICM is the only thing you did and the problem changed then I would say ICM. You also said it got worse with new MSD coil so that really leads me to believe that it is something in the ignition system. Since it seems like the heat is the factor that is coil or Icm 80% of the time. The coil has been changed so it's not the coil. I would go grab and ICM and try that and spacing it off the head is the best thing you can do for it. When you change the ICM you should go get thermal paste instead of grease that is used for mating CPU's to heat sinks in computers. If you have a compUSA near you you can pick a small tube up for nothing. This is what they come with from the factory to mate the ICM to it's heat sink.

ugod02010

Have u checked fuel pressure. Mine was acting pretty similar 2x now and both was fuel pump.

SS RRR

iTrader: (2)

I'm not sure this was covered, but did you try and unplug the O2's to see what happens? If not, do it and drive it for 10 to 20 minutes.
The other issue which happened to me is the car would drive fine until warmed up then start to hesitate. Found out the w/p was leaking onto the opti only once the coolant system would pressurize. Get your car to operating temp and see if the w/p weep hole is even damp or if you can see coolant anywhere around. There was so little coolant leaking that it would evaporate before it would hit the ground. I only found it by luck when I figured it was opti related, had just ran the car, jacked it up and saw the bottom of the w/p was damp.