hesitation, poor acceleration.. but smooth idle?

[kings-x59]

Crash, I don't know about the later model years, but I've been having a run of bad luck with TPS'. I'm on my third or fourth sensor (I've lost count). The replacements haven't been GM OEM, so that may have contributed to my issue.
If you have a digital multimeter the tps is not hard to test. Autozone's website has a good write up on testing the tps in their repair pages.

[crash]

I haven't got to testing the TPS yet. Or changing the coil. I can rule out O2 sensor and a bad cat. I decided by november of this year the van is going to need an emissions test anyway. being that once tested in Ontario the result is good for 1 year I'd get it done. passed clean with no issues. I asked about the readings and if anything pointed toward the O2 going bad or the cat plugging up. No on both counts was the answer.
I got to thinking that if it was an injector sticking as mentioned, that it would also be a rough idle. which it's not at all. super smooth.

I was also told today that under the cap and rotor there is some sort of small screen. it can gum/dirty up and can be cleaned. i've never heard of though. is the guy that told me flapping his gums in the breeze or is there any fact to this ?? he said his 4.3L S10 ran like this and once the screen was cleaned it was all good.

I'm thinking I'm down to this mysterious screen (if such a thing), TPS and coil. Also, someone mentioned a secondary coil in this thread.... where o where is that one?

[astrozam]

my 95 has a screen under where the dist cap sits,your cap is slightly different so i'm not 100% sure if its applicable to your yr,but they can get dirty and trap moisture,so its best to check.

[kings-x59]

my '89 distributor has two small screened vent holes. I've had moisture in distrubutors on other vehicles cause driveability problems and even no start conditions.

[crash]

this morning was the worst it's EVER been. we had two major thunderstorms roll through in the last day with VERY heavy rain. I never used the 99 yesterday.

this morning I drove it the 4min skoot into work and even when my foot was barely on the gas pedal it was stumbling badly. i pressed harder on the pedal and it just sped up a bit and kept on stumbling. it didn't throw any codes again. i was hoping to have one of our customers scanner for the wknd but that didn't come together.

obviously, all that rain has made it MUCH worse. it was stumbing and lurching so much so i thought i was going to be walkin to work

[crash]

I tried a new TPS this morning. No change.

I tried a new coil this afternoon.. seemed to help out somewhat but that could be because it's been hot and dry here the last few days...... I even soaked the dist cap and wires down with a squirt bottle... didn't seem to change anything.....

I've also just created a thread in the transmission section.. not sure if the two issues are related.. but take a sec and read if you can and please post your opinions/thoughts.

thanks
rob

[crash]

the saga continues....

like I mentioned. not the TPS, not the coil. tomorrow I'm going to try another cap and see if maybe I got a bad one out of the box. apparently, not unheard of.

I can't think of anything else at this point so I'm open to any suggestions.... (still haven't got my hands on that scanner). at least based on Dean's reply to my tranny posibilty I can lay that idea to rest. phew!

things I haven't tried. pickup and ignition module. both which I figure would either cause the van to either not start or idle real bad, which it doesn't ....

thanks
rob

[crash]

tried a new cap this morning. no change

[crash]

tired a new 'hall effect pickup' aka camshaft position sensor on the distributor this morning. no change. hesitation still there.

one last thing to try before I take it in and pay the big money to have a shop scan it with an OTC Genesis scanner.

the ignition module. if only I could find it on my 99. on the 93 it was under the distributor. I can't find it on my 99. anyone have any ideas were it's mounted? ..

EDIT: found it .. mounted to the side of where the coil is.

changed it .. still no change. well it starts real quick now (as soon as the key is turned, it's running) other than that.. the hesitaion is still there. ](*,) ](*,) ](*,) ](*,)

i'm absoooolutely out of ideas.......

[Rileysowner]

I wish I could help, but I am interested in what it might be.

[crash]

you and me both are very interested to find out.

two techs I talked to said use a GM cap. I called our local GM dealer who buys from us for several 'white box' items. They said that their delco caps and rotors are made at the same place to the same specs as ours. the company that makes them is standard brand aka blue streak.

so much for that idea.

that was my last resort before hitting up a shop for a scan

[crash]

a tech just happened into the shop and scanned it for me with his snap-on scanner.

two codes in memory.

P0300 - random misfire (history shows cylinder 1)
P0452 - evap pressure sensor signal (low or short)

in his opinion, he said that the evap code would only effect emissions nothing to do with the misfire/hesitation.

anyone know which is cylinder #1? so I can pull the plug and check out that plug

[phr1$k37]

Please verify my post (I dont have my haynes with me at work but google is what I did):


4.3L engine Firing order: 1-6-5-4-3-2 Distributor rotation: clockwise

Ratz I was going to suggest to swap spark wires with what you have in the engine already and rescan ... but you dont have a scanner. When I got my new I had wire problems. Then back in Oct 2006 a REALLY bad stumble (sounded and felt like a threw a rod) - changed dist + rotor no go then did sparks and wire and it was cured.

[crash]

thanks.. I'll check when I get back in buy my 99 cap isn't laid out like that at all ... the 2 pass side wires go to the pass side of the cap and same goes for the dvr side go to same side of cap

[phr1$k37]

Yah I was wondering about that ... I assume my 97 is the same as your 99 :p