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zhd1000
03-12-2007, 04:56 PM
under slight to moderate acceleration (like regaining speed after turning left or leaving a red light under normal driving conditions) i occasionally get a small hiccup.. sometimes 2-4 in a row.. no SES codes have been thrown.. i installed DHP v1.0 in the fall sometime and installed FFP pulley (and had to get a new 24x sensor bc i broke the old one ;crap) a couple months ago.. i didn't get a CASE learn after either mod.. does anyone think that the hiccups could be caused by NOT having the CASE learn done? any other thoughts as to what may be causing this? it starting on Friday when the temperatures have graced northern illinois with the 60s and heavy rains.. don't think that the extra moisture has anything to do with it because it did it today and it's not raining.. any ideas? thanks.

zhd1000
03-12-2007, 05:20 PM
update report: my dad just got back from taking the ga a short trip up the interstate and he said he could cruise at around 65 fine but when he would sneak up to around 70 and the car would sputter, he would back off down to 65ish and it would be fine.. again, no codes..

gectek
03-12-2007, 05:57 PM
usually that is spark or fuel related, more spark than fuel though. id look at the fuel filter though anyway, and also when u get the hiccup, have a scan tool on it to read which cyl is the culprit, or if it is across the board.

polo77
03-12-2007, 06:51 PM
My brother had a similar problem with his 98 saturn. only hiccuped when he took off. NOw it died and wont turn over. Found out to be a fuel pressure regulator.

zhd1000
03-12-2007, 08:11 PM
usually that is spark or fuel related, more spark than fuel though. id look at the fuel filter though anyway, and also when u get the hiccup, have a scan tool on it to read which cyl is the culprit, or if it is across the board.


hmm.. i changed the plugs to ngk tr55 maybe 2 yrs ago.. stock wires.. car is reaching for 75k miles, maybe the fuel filter is going.. how do i check that? just take it out and replace.. it's only $15 on pfyc.. i wish i had a scan tool at my disposal tho

any thoughts about not getting a case learn done?

Sprucegagt
03-12-2007, 10:02 PM
I don't think the case learn is your problem. Instead I'm with gectek and change your fuel filter if it's more than a year old.

gectek
03-12-2007, 10:57 PM
that is usually a random misfire code, and maybe a crank/cam or crank/crank correlation code, but it wouldnt misfire due to that i dont think. its either one or the other though, fuel or spark. and just cuz the wires are newer doesnt mean they arent leaking voltage or inducing voltage, and could be a bad coil also or ICM...just a few thoughts

zhd1000
03-13-2007, 11:58 AM
what do you mean by spark? the plugs or the wires or both? or something else? so you think it's either bad fuel filter or plugs/wires?

gectek
03-13-2007, 01:54 PM
no there is more to spark than plugs and wires, there are the coils, ICM, crank sensor(x2) and the cam sensor AND all the wiring included in that. sometimes u will get induced voltage from one of the wires laying on another wire or another plug wire. or a bad coil will show up sometimes either under load or under no load. the only way to test a coil for good operation is with an oscilloscope or a DSO. any other misfire can be detected with a scan tool. if you go get the history codes read then maybe they will tell u if it is a localized cylinder. if it is then i would look at something cyl specific...like a plug, or maybe a valve...alot of things really. the best thing to do would be either to buy a cheap DSO off ebay and use it, that way you can even rent it out to other people to use, or a scan tool, or take it to a good tech and have him run the tests. i would def do the fuel filter first though. and since it usually shows under load, it would either be fuel or spark. i dont see anything else making a bad environment than that under load.

but also anothing thing that shows up under load could be timing...maybe a loose timing chain

zhd1000
04-15-2007, 09:11 AM
alright.. so i replaced the fuel filter and it had been about a week of perfect driving.. so i assumed the problem was the filter.. but yesterday it began to do the same thing.. where do i go next??

zhd1000
04-16-2007, 04:07 PM
a little more info..

the hiccup/sputter is definately back.. new fuel filter and nothing for a week and then it's back to normal..

today i was trying to pay attention to when it was occuring and here's what i got:

it occurs the most right after the 2-3 shift
also occurs right after 1-2 and 3-4 but not nearly as often

occurs when crusing above 65mph
occurs when accelerating (moderately, say 25-50% throttle?) mostly around 30mph

DOES NOT occur at WOT.. went 0-60 and 40-90 and it didn't happen until i started crusing at 65-70mph
also doesn't occur under heavy accelerating (below WOT) either..

:confused:

please help

i really would like this problem to not be in the transmission ;crap

also, i'm planning on going to the drag strip this weekend, do you think that this condition could be dangerous to the motor/trans if put under that kind of stress.. it doens't happen at WOT so i'm thinking no.. but this seems to be a lack of fuel getting to the engine and that wouldn't take much to hurt the engine..

also, NO SES/SVS light

mfuller
04-16-2007, 06:10 PM
I was experiencing the same problem a while back. 20 bucks says the PCM is commanding too much timing. Put your stocker back in and see if you can duplicate the problem.
With the FFP pulley and the DHP, you really should get a CASE learn.
I could try to do it for you - I think my PowrTuner will do it.

zhd1000
04-16-2007, 07:51 PM
hey that would be awesome if you could do that for me... i'll try putting the stock PCM back in, we'll see what that will do..

zhd1000
04-18-2007, 08:08 AM
alright.. i swaped back the OE PCM and so far i've driven the car from machesney to dekalb.. i still got the hiccup/sputtering at 68-70mph.. i got a little on the 2-3 shift once.. so i'm guessing if i give it a little bit of time it'll come back.. so as far as what's wrong, i think the PCM is out.. though it'd still be nice to get a CASE done..

zhd1000
04-19-2007, 07:36 AM
any thoughts?? what should i try next?? could it be the fuel pump or a bad injector? i wish an SES light would just come on so i could figure this out :bleep:

zhd1000
04-19-2007, 08:22 PM
well i put the DHP back in and the DHP seems to amplify the problem.. you can definately feel it during the 2-3 shift with DHP and hardly at all with stock..

Sprucegagt
04-19-2007, 09:18 PM
Does it sputter real bad when lugging the engine? Say trying to go up a hill at 45 MPH.

zhd1000
04-19-2007, 09:35 PM
Does it sputter real bad when lugging the engine? Say trying to go up a hill at 45 MPH.

nope.. just cruising at 67-70 and during light-moderate acceleration around 30-35 (frequently during or immediately following the 2-3 shift)

Sprucegagt
04-19-2007, 10:20 PM
One more question. How bad was the fuel filter you changed out? Did you get a lot of black gas out of it.

zhd1000
04-19-2007, 10:36 PM
i didn't really check out the filter that much.. as far as the gas that came out of the filter no it wasn't black.. looked like normal fuel to me..

could this be a problem with the cat?? i don't have a rotten egg smell or anything.. just wondering bc my TOG and SLP are both 2.5" and the stock cat is 2.25".. maybe it's finanly clogging up? and the TOGs are just nickle coated so they aren't flaking..

gectek
04-20-2007, 10:45 AM
to check the cat you should use the pressure test, but it doesnt sound like a fully clogged cat, maybe partially clogged, but it just sounds kinda funny...i would look for bad connections or a common thread on those 2 occations, like with an apply chart on a trans, if ur trans slips from 2-3 and 3-4 and during a 4-3 downshift, then it is this(if all elec components check out ok), so there seems to be a common point

Sprucegagt
04-20-2007, 06:16 PM
Well I don't think your problem is in the ignition system. If it was it would breakdown under high load and you don't have that. Instead you have it happening under light load conditions and its strange that it went away after changing the filter. That makes me think it's fuel related somewhere.

zhd1000
04-21-2007, 08:17 AM
is there a way to hook up a tech2 to the car and see what's going on without having any codes??


so i'm thinking it's fuel related too.. so where's the next stop? fuel pump? injectors? where else in the fuels path could be causing a problem?

gectek
04-21-2007, 12:13 PM
yes the tech 2 will give the person live data from all of the sensors and inputs.

zhd1000
04-23-2007, 03:32 PM
bump.. anyone.. any more ideas?? where should i try next??

Gizm0815
04-23-2007, 05:34 PM
Fuel Pressure Regulator

blk_grn_97GT
04-24-2007, 06:55 PM
i have been having the same problems and i have hooked up the tech 2 and only found that under light load the #3 cylinder would missfire, at one point in time i had a code 0303 which is #3 missfire but that didn't help, i had replaced the fuel filter, air filter, plugs and wires, did a vacuum check, fuel pressure check, checked FPR and found nothing, so i have an extra set of injectors and i am going to go ahead and change injectors just cause it has came to that point and its not a bad job, most people have been saying since it has 225,000 miles that its a compression problem or valve problem but everything checks out surprisingly well for a 3100 with that many miles so i figured that its worth a shot.

lone_wolf025
04-24-2007, 08:16 PM
bump.. anyone.. any more ideas?? where should i try next??

Maybe its a tranny issue. You mentioned that with the stock PCM it was less noticeable...I assume your DHP jacks up the line pressure? If that's the case perhaps its something that is beginning to fail that is amplified by higher line pressure? How much would it cost just for a pan drop?

Fuel pressure regulator might not be a bad thing to check too like Gizmo said.

gectek
04-24-2007, 11:29 PM
well the misfire under light load would usually be spark, thats what was bad on mine, and also the MAF was bad, which irritated the issue. too dirty to clean so had to get a new one, changed those 2 things and that was it

Sprucegagt
04-25-2007, 06:16 AM
well the misfire under light load would usually be spark,

How so? Light load is second only to idle in no load being placed on the ignition system.

zhd1000
04-25-2007, 06:28 AM
Maybe its a tranny issue. You mentioned that with the stock PCM it was less noticeable...I assume your DHP jacks up the line pressure? If that's the case perhaps its something that is beginning to fail that is amplified by higher line pressure? How much would it cost just for a pan drop?

Fuel pressure regulator might not be a bad thing to check too like Gizmo said.

yeah the DHP does increase the line pressure, even though this does occur frequently during (or immediately following) the 2-3 shift, which may suggest something in the transmission, it also occurs at crusing 68-70 mph (don't know about any higher really, i back down the speed as soon as i feel it). so if the problem occurs at a crusing speed couldn't i rule out the tranny?

zhd1000
04-25-2007, 06:32 AM
i went to the track on sunday and here (http://www.students.niu.edu/~Z082720/byron422.htm) are my results.. after the first 2 runs i swaped out my DHP for my stock PCM with the intention of reducing the timing to see if the car would run better... this resulted in fairly same times (the low of the day was with the GM tune though, remembering that i only gave DHP 2 chances too..)

just thought i'd share.. don't know if this will shed any light on anything..

gectek
04-25-2007, 10:43 AM
How so? Light load is second only to idle in no load being placed on the ignition system.

because at light load the voltage spikes can start to induce glitches, or agitate a problem. i used a DSO on my car and that is the only way i found it. it was barely there at idle, and when i gave it some throttle, the glitch would show up and get bigger, but under WOT the waveform would be so distorted and change so fast you couldnt tell.

Sprucegagt
04-25-2007, 08:28 PM
So what did you change to fix it and how does this imply that misfire under light load usually means its an ignition problem? That sounds to me you had a unique case. Not something that is common.

gectek
04-25-2007, 08:30 PM
i changed the 3-6 coil and the MAF as well and it went away...and yah it maybe was unique, but i have seen it before on vehicles with HEI.

Sprucegagt
04-25-2007, 08:36 PM
You mean DIS. HEI went away with the distributor.

gectek
04-25-2007, 08:39 PM
no i mean HEI. ive seen it with both systems

zhd1000
04-30-2007, 05:13 PM
ok i've had my OE PCM in the car since 4/22.. i've filled up with 93 after the track day and everything seemed fine.. today i fill up with Mobil 87 knowing that i had the original pcm in there (and regular was $2.999)... and about 35 hwy miles later that car feels like a dog. could this be related to my problem at all? or is it more of feeling the reduction in timing and using the lower octane fuel?

zhd1000
06-11-2007, 10:10 PM
so.. this is still going on.. and i'm starting to get real annoyed with it.. enough to actually do something about it..

where should i look next? all i have done is replace the fuel filter.. so check the gap on the plugs (what are they supposed to be at anyway)? check plug wires? can i check the coils?

gectek
06-12-2007, 12:30 PM
the gap on the plugs should be .060 in...says that in ur owners manual i think. also yes u can test the coils, but it isnt a very accurate test because u are testing them without a load on them, but u can still do that. just use an ohm meter. should test little to no resistance on the primary side(small slits) and about 5-9k ohms on the points. but also i would take ur module in to get it tested at an auto parts store that can do that. if that doesnt find the problem, then u should go to a mechanic with an oscilloscope to hook up to the wires while the car is running to look at the wave form patterns. that will narrow it down to coils or module. also if you scan it, look at the maf readings and see what u can find.