Rough idle and hesitation on acceleration

[bjeeper04]

Re: Rough idle and hesitation on acceleration

you can get a 3 bar map sensor from the dealer for like 60 bucks with the pigtails, duramax diesels use a 3 bar as well. And while I thought I had things figured out with my own truck by replacing my map sensor and O2 sensor, for a while it was sweet as cherry pie, until I went down to southern utah and filled up my empty tank. Than it was back to its old self. between 3000 and 4000 rpm its great, anything below and it studdards really bad. above and it makes a weird ticking noise. Its not a knock, at least I don't think so. I am going to check the ECU, I'll see what that does

 

[Inferno]

Re: Rough idle and hesitation on acceleration

Still can't drive... code 35 and 42.. now change ignition module..

 

[sbwrench]

Re: Rough idle and hesitation on acceleration

I had a really bad hesitation with mine. Sometimes check engine light sometimes not. It was code for the distributor output. Changed everything, good tune up, ect. No better. Changed O2 sensor for the hell of it and it ran like a new truck. Been running great for the last 5k miles. Probably just jinxed myself!

 

[Inferno]

Re: Rough idle and hesitation on acceleration

is there a way to test MAP ?? with a multimeter or whatever ??

 

[Foot Performance]

Re: Rough idle and hesitation on acceleration

is there a way to test MAP ?? with a multimeter or whatever ??

Use a scan tool or data master and a hand held vacuum pump/ also a regulated air nozzle

scan tool will should read what pump or air regulater reads :tup:

 

[Inferno]

Re: Rough idle and hesitation on acceleration

Changed o2.... started... idle was high, 2100ish... ok let her run for 5 mins or so.. still didn't drop.. shut the hood, bogged almost stalled.. back to the computer.. shake it and idle goes up and down... engine light on and off... I already put a new ecm in it... What is the white box attached to it ??? the brown est wire was corroded, cut the plugs and hardwired.. still same... smells funny too!

 

[Foot Performance]

Re: Rough idle and hesitation on acceleration

Changed o2.... started... idle was high, 2100ish... ok let her run for 5 mins or so.. still didn't drop.. shut the hood, bogged almost stalled.. back to the computer.. shake it and idle goes up and down... engine light on and off... I already put a new ecm in it... What is the white box attached to it ??? the brown est wire was corroded, cut the plugs and hardwired.. still same... smells funny too!

If you shake the computer and thing go crazy it almost has to do with it I would make sure ALL the terminals are making good conection and maybe check prom :tup:

 

[Inferno]

Re: Rough idle and hesitation on acceleration

Bent all pins, used dieclectric grease, re connected all... no difference again this morning no start until I grabbed the comp and yanked it around... only thing not changed is the lil white box and the prom.. I had another one before but I can't find it.. is there somewhere I can buy one ? No one around here has one......

 

[Foot Performance]

Re: Rough idle and hesitation on acceleration

Bent all pins, used dieclectric grease, re connected all... no difference again this morning no start until I grabbed the comp and yanked it around... only thing not changed is the lil white box and the prom.. I had another one before but I can't find it.. is there somewhere I can buy one ? No one around here has one......

The prom or the white box???

I think the white box it the DRAC

You can get a prom from the dealer my parts guy is gone but I may be able to get one a little cheaper if you want :tup:

 

[Tooky]

Re: Rough idle and hesitation on acceleration

All you guys with the bogs/hesitations on acceleration that changes depending on your throttle position..... I would recommend getting a wideband O2 sensor. That way you can watch in real time, if your engine is going lean at the same time it's hiccuping, then you know it's a fueling issue that can be corrected in your chip. What mods do you all have? If your truck is anything other than bone stock, there's a good chance your condition can be corrected in the chip (assuming it's not something mechanical like bad lifters or vacuum leaks etc.)

Without a wideband you are just guessing on the fueling. The guy who described getting passed by Corollas and hiccuping going up a hill; in my experience, that's exactly how they act when they are going lean (like 16:1, 17:1 instead of 14:7 or richer).

 

[#2875]

Re: Rough idle and hesitation on acceleration

Still can't drive... code 35 and 42.. now change ignition module..

what do you mean by this? did you change the ignition module or not? i change mine every 2 oil changes now as preventative maintenance after i got tired of limping to the auto parts store once a year.

 

[Inferno]

Re: Rough idle and hesitation on acceleration

I did change my module, with no difference... I have as follows... Walbro 255 Fuel Pump, AFPR, 3" Exhaust and 3 Bar Map.. as of right now the truck will sometimes Run and drive fine, others times stall sputter bog back fire out of intake... only sometimes though.

 

[wantingasy]

Re: Rough idle and hesitation on acceleration

You have 3 bar map in with the 2 bar chip?

 

[Inferno]

Re: Rough idle and hesitation on acceleration

I don't think so, maybe... I have the stock chip, with the piggy back memcal, and the 3 bar... thats why I want to start fresh with a new chip and MAP sensor.. but I can't find anyone to burn one for me...

 

[wantingasy]

Re: Rough idle and hesitation on acceleration

I don't think so, maybe... I have the stock chip, with the piggy back memcal, and the 3 bar... thats why I want to start fresh with a new chip and MAP sensor.. but I can't find anyone to burn one for me...

You should have the stock chip in the computer, with stock piggyback, then the 2 bar map. Here's the link w/ numbers for identifying the 2 bar map http://www.syty.net/forums/showthread.php?t=37016&highlight=bar+map+numbers HTH :tup:

 

[odium]

Re: Rough idle and hesitation on acceleration

Sounds like quite a few are experiencing this issue. Has anybody ever finally figured it out short of rebuilding the motor?

 

[2fast4u]

Re: Rough idle and hesitation on acceleration

Still mucking with mine. A few times it ran simply PERFECT. So, i doubt i have a blown intake gasket. But, most of the time i hear a miss at idle that seems to go away after a few thousand rpm's.. tomorrow i will take the day off and devote it to my Ty. I will install my new dist. and Another set of wires, and we'll see how it runs. Ill do a write-up

 

[artisticent]

Re: Rough idle and hesitation on acceleration

It would be great to know what this is. I am sure that at least 60% of us have the same problem. I am dropping in a new motor that I know to run excellent this coming week. I will know soon if its the motor or electrical. In the middle of the swap I will clean up some wiring in the engine compartment but nothing more.

Nathan

 

[2fast4u]

Re: Rough idle and hesitation on acceleration

Sounds like quite a few are experiencing this issue. Has anybody ever finally figured it out short of rebuilding the motor?

Different answers for the same problem, im sure. But, heck,.. It sure be nice to hear more write-ups on how our members fixed their problems. Its rare.

 

[syclone1100]

Re: Rough idle and hesitation on acceleration

Well I have been fighting this problem for awhile, instead of throwing big $$$ at the problem I started with easy things, so here is what I have done so far. New IAC,TPS, and MAP no change, replaced plugs gapped to .30(NGK URIX) & coil(MSD) (almost an unnoticable change) Then changed plug wires to RPM wires (did make a slight difference) Just got done replaceing the cap & rotor (stock replacement) this did cure the problem for a day then it came back again after I adjusted the FP so tonight I will lower it to where it was before and see. If this doesnt help I will take a look at ground wires and then step up to Upper & lower intake gaskets, I do know my TB has a very small leak in the usual place and I have a Holley 52mm ready to go on once I figure out how to get the TPS to work correctly with it (Ill start a new thread on that subject). Now I will try to keep this updated with any other things I do to fix the problem, so that others can learn and fix this PITA problem..