95 small block - Sluggish acceleration - is it from ESC?

[AuroraGirl]

I dont know the gm terminology in 95 for a small block with the change of centuries coming and computer systems replacing HEI etc all that, i am a 99 park avenue driver and i own a 80 gmc. my dad and uncle have a 96 and 95 small block ,respectively, in a GMT 400 96 1500 but a 95 GMC Van(3/4 ton van)
I dont know the van platforms, but he has EGR and he has a distributor.

The van runs great, no codes per my tech 2.
Its just sluggish on get up and go especially starting. on my tool, he idles 14-20 degrees advance according to my tool. I told him to check his base timing as proper which he claims is but he will check again. He just had a lot of pulleys replaced because they were wobbling and worn etc. He also has a tad bit of shake on idle but not noticeable unless you really care to think, cup of water on dash would show you that. However, the scan tool had recorded a lot of knock sensor activity, but i dont know if that means its pulled timing that many times(large nunmber) or if it just was sensor detected but maybe not bad. I dont know.

SO.,

I ask if his sluggish acceleration could be from his ESC or KS system pulling timing because of engine mounts or maybe a dampner not sufficient. I read somewhere the old ssensors were too sensitive???

Its mechanically pretty sound with 80k miles and all systems say go on the tool. it runs smooth. oil looks decent, leaks a bit, coolant is flushed because it was brown but he doesnt notice any burning, he leaked but he changed waterpump.

I cant comment on proper engine shake with a small block because my motor mounts are TWISTED on my truck as well as my np208 mount is snapped LOL

Expert help appreciated. If it is ESC, can it be bypassed like the old days or is it complex

 

[PlayingWithTBI]

on my tool, he idles 14-20 degrees advance according to my tool.

That's pretty much normal.

1st thing I'd ask is, what's your fuel pressure at idle and when you accelerate? Running lean can cause KCs. Do you have any loose exhaust pipes which may be hitting the frame? Are most of the KCs from starting the engine (that's normal too)? How are your fuel trims, INT/BLM, when in closed loop? O2 cross counts OK?

 

[Schurkey]

There's forty different things that can cause lazy acceleration. Not all of them are related to the engine.

Verify fuel pressure.
Verify cranking compression on all eight.
How old is the O2 sensor?
How old is the catalyst?

Sounds to me like you have excessive knock sensor activity, which could be a failing sensor, a harness problem, or engine issues--lean fuel mix, excess carbon in the combustion chamber, excessive engine internal noise, etc.

NO, you shouldn't remove/disable the ESC/knock sensor system. Fix what's making it go crazy. The difficult part is figuring out what's making it unhappy.

 

[AuroraGirl]

There's forty different things that can cause lazy acceleration. Not all of them are related to the engine.

Verify fuel pressure.
Verify cranking compression on all eight.
How old is the O2 sensor?
How old is the catalyst?

Sounds to me like you have excessive knock sensor activity, which could be a failing sensor, a harness problem, or engine issues--lean fuel mix, excess carbon in the combustion chamber, excessive engine internal noise, etc.

NO, you shouldn't remove/disable the ESC/knock sensor system. Fix what's making it go crazy. The difficult part is figuring out what's making it unhappy.

old 80s ESC was a mess and frequently doesnt work right. I have no idea what improvements TBI or ECMs brought but on a carbed(mechanical) HEI... esc is usually a chopping block item.

Its why I asked you
experts


i have not had him check fuel pressure. ill ask him if he can find the port and ill bring gauge. i had him get a new pcv and i cleaned his current one. gunky. vacuum lines were fixed. Compression can be done but im not sure how easy getting to some of those plugs will be or if its easy.

Original cat, prob original O2. its just one o2. ill have to check knock activity on startup and see if thats when. good idea to check

That's pretty much normal.

1st thing I'd ask is, what's your fuel pressure at idle and when you accelerate? Running lean can cause KCs. Do you have any loose exhaust pipes which may be hitting the frame? Are most of the KCs from starting the engine (that's normal too)? How are your fuel trims, INT/BLM, when in closed loop? O2 cross counts OK?

INT BLM I Know those are but i dont think my scan data said them, i cant recall
FUel trim I want to say was a positive 4% but when idling in closed it was right around 0 and if you got on it it would level where it had to go for instant. long term i reset last iwas there

If relevant, his idle was slightly low and i did a relearn on it. I forgot that

 

[AuroraGirl]

also last i saw him i told him to get Ac compressor bypass pulley. he has a compressor(not sure which model, forgot) but its a delphi, anyway, its got some wobble on the clutch and makes racket and resists turning. He doesnt plan on using AC but would that create enough vibrations or noise maybe?

 

[PlayingWithTBI]

He doesnt plan on using AC but would that create enough vibrations or noise maybe?

That's a possibility.

 

[AuroraGirl]

That's a possibility.

I’ll make sure before I Chase potentials that he has that stuff nailed down then

 

[PlayingWithTBI]

I’ll make sure before I Chase potentials that he has that stuff nailed down then

Yeah, while the engine is idling, you can tap the block with a hammer and you should see KCs

Note: If you do change the Knock Sensor you should change the ESC module too in order to ensure they're matched.

 

[Schurkey]

also last i saw him i told him to get Ac compressor bypass pulley. he has a compressor(not sure which model, forgot) but its a delphi, anyway, its got some wobble on the clutch and makes racket and resists turning. He doesnt plan on using AC but would that create enough vibrations or noise maybe?

Why not just put a fresh bearing on the compressor clutch?

 

[thegawd]

Shurkey, I may need to do that on my burb, its squealing, just started. my ac is ****** since the rear lines were ripped off. I thought about removing it all together but its needed for defrost and now its squealing. I guess probably because all the refrigerant leaked out and that's what keeps it lubricated up right? I know nothing about AC! is this a good hypothesis? LMAO can I bypass the rear lines, cap them off and recharge the system? or is the bearing screwed and also needs replaced? of course If it seizes in guna be royally screwed. I'm guna have to look into this or maybe just buy the other belt and bypass it for now.

haha

Al