nimrod.sixty9

iTrader: (5)

Seems to run just fine, but sometimes it seems like it’s missing and takes longer to shift; like power drops and trans just doesn’t shift. Deff noticeable on bridges (or likely hills for those of you not living on flat earth), but not at all times. It is way more prevalent with the AC on.
Giving it more throttle seems to smooth it out, sometimes letting off and letting it shift and throttle again will make it go away too; but only for that moment. It is random as in I can have a day where it happens here and there, or not happen for days. It always only lasts a couple of moments; otherwise runs fantastic.

So this is warm, under load, under light throttle or accelerating, conditions.
Plugs are fairly new. PCV is clean.
New Throttle Body (includes TPS, no IAC), ICM, Coils, EGR, EGR pipe.
No CAT; noticeable change when removed.
All fuel pressure tests were good.
No codes

A couple of months ago it ran hot (issue existed before) while driving though mountains and noticed the fan wasn't working, apparently the previous owner half assed a wire to batt. I noticed some puddling of antifreeze on the intake, behind the alt. I added water, kept running warm while in the area but not hot. Haven't had an issue since being back in flat Florida. How would this AF get in this location? Is this issue related somehow? Anyone have the diagram for the fan?

Fuel Pressure test;
https://www.youtube.com/watch?v=scYd...ature=youtu.be
Harmonic balancer;
https://www.youtube.com/watch?v=Ppci...ature=youtu.be
Engine running noise;
https://www.youtube.com/watch?v=k33t...ature=youtu.be



2002 3.8 Firebird

slpfirehawk415

Sounds to me, since it runs fine and is intermittent, like you are talking about a spark issue. When was it last tuned up? First most obvious and easiest thing is pull a couple wires and resistance test against spec resistance (ohms per foot). If you don't have a DMM to read that another test is put it in a really low gear going up an incline so you will be close to full throttle at low RPM just lugging up the hill. This will stress test the ignition system. It would be my guess that under this stress test you will find heavier missing which will confirm the ignition problem. Usually coil packs wouldn't be the first thing I would check but wires and plugs seem simple and probable in this case from what you describe. Hope this helps

wssix99

iTrader: (5)

This fits within the parameters of a classic dirty MAF.

Darth_V8r

iTrader: (4)

I just had to completely retype this reply, because I assumed an LS1, not a 3.8.

As to the antifreeze getting on the intake behind the alternator, check the throttle body. On the 3.8, coolant runs through the intake to heat/cool the throttle. There is a seal between the throttle and intake that might have cracked. Also, VERY common, is that a throttle bolt gets lost in the shuffle during a repair and someone replaces it with one slightly too long, and it never seals completely properly due to bottoming out.

Only thing that's bugging me there is that the Camaro I had ran COLD when that was the issue, not hot.

Lup

I'm with slp firehawk on this one. My guess would be plug wires are bad. My experience I found the 3.8v6 to be very hard on plug wires. The 3.1 and 3.4 don't seem to kill plug wires as fast. Make sure you get good wires and not $10 special.
I like to use the power break method to diagnosis bad wires. Put car in drive, left foot on the break, and give it gas. If it cuts outs, I'd replace plug wires. Sounds like you ready replaced other spark stuff

--Kyle

LS6427

iTrader: (2)

Telling sign of a failing o2 sensor(s).......they will cause you to run slightly rich....then when you crack the throttle open more that rush of air getting in will remedy the rich condition momentarily..and while you remain on the throttle accelerating.

Get a scan before you spend money chasing the 1 million different things it could be....see how the o2 sensors are switching with the engine running at full operating temp.

.

nimrod.sixty9

iTrader: (5)

All replaced except wires. Again, I can test load and it would be perfectly fine; even for days. Then Ill have it for days.
It has been fine under all conditions, and bad under all conditions.

Replaced with TB.

I always post here, mine was LS1, hers is the 3.8
All V6 forum are dead now as most of them are into LSx. The knowledge remains tho. Sorry.

TB was just replaced; new gasket, all bolts are original.

I believe this one will do it cold as well.

Ive gassed it and ran perfectly, havent power braked it yet. Ill try that today. Ill prob go ahead and replace the plug wires tho, or at least check the resistance.

That's not what happens, sometimes it will stop it. Other times I have to let off. Most of the time, it just stops whenever. It is really that random. Sometimes I even forget it;s there, then one day I gets pissy.

Been some time since I last scanned, tho it was acting up at that time as well, nothing stood out. Ill get out ScanXL and make another run. Itll be my luck itll run perfect the whole time...



How about intake gasket leak? After much more digging and reading, it looks like they also suffer from this fairly commonly.

Thanks all!

LS6427

iTrader: (2)

Scan it....see what it shows for o2 sensors.

.

Darth_V8r

iTrader: (4)

Sorry, I didn't mean to look pissy with that post. In general, when I encounter a motor that runs very crappy with no or very little throttle but then smooths out with more throttle, the first thing I think is vacuum, and very often it ends up being true. Vacuum would also explain why it wants to especially die when you brake hard, because you've introduced a second vacuum leak with the brake pedal.

If the gasket between the upper and lower plenum is compromised, that could cause the coolant leak AND the vacuum leak. Before tearing into it just to find out that isn't the issue, maybe a smoke test or the "WD40 while logging" test to see if the millivolts on the sensors change when you spray certain spots around the intake.

If you get a day where she acts up, just hook in the scanner, and shoot WD40. If it's vacuum, you'll find it.

nimrod.sixty9

iTrader: (5)

It's all good, I did not take offence

FYI, Ive searched for vacuum leak before without avail. Also, It does not die at all when braking.

I should be more clear when explaining the throttle situation. Throttle does NOT clear up the issue when it occurs, only feels like it does. Pretty much just bogs more and more with more throttle; that's the power loss Im referring to. If throttle rests at same position when the issue occurs or throttle returns to same position, it runs smooth until it just goes away after a few seconds.

Taspeed

iTrader: (1)

ever find a fix to this...i've got a similar issue in my 99 ta. it seems like you unplug about 4 coils and no codes. let off the throttle for about 30 seconds and feather the gas and it seems to go away. its almost always happening from a dead stop off idle. Ive replaced everything but the maf and cam/crank position sensors. its pissing me off I am concerned that it may be a bad ecu.