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'89 eighty eight


swingline
02-14-2007, 03:56 PM
my olds misses bad under load. it has a 3.8. it has low vacuum(about 12") but i can't find a leak. it cruises just fine but i can't accelerate, i have to rap out the gears so it won't miss when it shifts, hills suck.

now, i have ruled out fuel problems, i have good pressure under load, cleaned injectors thoroughly, symptoms never changed.

i made sure the exhaust isn't restricted, symptoms stayed with straight pipes.

i tested the spark with a spark tester on all plugs while reproducing the symptom and i have good spark. new plugs and wires.

i have no codes and the sensor values seem normal while monitoring with scan tool.

i think i have it narrowed down to two things i just wanted some opinions or help if someone has dealt with this.

i think that either the timing chain is stretched or the idler broken causing the valve timing to be off, causing more problems under load

or..the valves are so caked with carbon buildup they don't seal properly.
oh, it sat for about 4 years before i started driving it and it's done this all along, about 6 months now.

xeroinfinity
02-15-2007, 09:12 AM
If it sat that long I'd drop the gas tank and clean it!!!
IT is probly varnished up inside there and probly varnishing up your engine now.

Could try changing the fuel filter & adding some Seafoam and see if that'll clear it up.

What were the Values on the injectors ?
You said you cleand them, but did you test them other wise to see if they are working 100% ?

Pretty sure if the timing was off it would run poorly at all stages of throttle.

Hope that helps!

swingline
02-17-2007, 01:11 PM
the tank was empty while it sat, but i have changed the pump and filter, put seafoam in the tank three times. i also ran it on straight seafoam with a fuel injector cleaning tool that uses compressed air and the schrader valve.

none of that made any noticable difference.

it dose run somewhat poorly in all circumstances, but under load it get's so much worse, i fear when i drive it someone behind me is calling me "grandma".

i did get some top engine cleaner, but the nozzle broke. i did the best i could and the first time i drove it after that i thought there was improvement, then it seemed to get worse.

that all brings me back to dirty valves.

i have tested the injectors for pulse but have not done a flow rate or balance test. maybe i'll take the fuel rail off and watch em pulse and then a balance test.

xeroinfinity
02-17-2007, 07:19 PM
Even though the tank was empty you'll still have it in the lines throughout.

And as you suspect the valves are probly a little dirty too.
Seafoam will clean them a bit.
You'll need to find a vacum port on the intake(not the pcv).
Warm the engine realy good.
Pour 3-4 oz of the seafoam in a container.
Connect a piece of small hose to the port.
Start the engine and put the hose in the container, it'll suck the stuff out and it'll clean up the intake/vavles.
Shut the car off and let it set for a few.

These directions are on the 16 oz can of seafoam.
I forget exactly how long to let it run before yo shut it off :uhoh: :banghead:

See if that helps :thumbsup:

btw- you may see smoke rolling from the exhaust, this is normal when cleaning like this.

swingline
02-18-2007, 02:15 AM
well, i cleaned the valves with the top engine cleaner in the manner you described before and thought it made a difference.

earlier i did a injecter balance test (should have done it a long time ago) and found one dead injector and two weak ones. i got a used set off an earlier model, swapped the three and got a definite improvement but it was still off.

i pulled the fuel rail and watched them spray and found out only one of the ones i replaced worked, but worked well enough for an improvement. i was in the process of changing the other two when i had an encounter with fire!!!

it was quite exciting, and nothing important was melted so that was great. should have disabled the ignition, but of course hindsight's always 20/20.

anyway i threw two others i had in their and decided to try another day. there was a small improvent over the other two, and i have one more to try.

i just don't want to buy new injectors, they are 106 bucks a pop.

xeroinfinity
02-18-2007, 09:48 AM
Fire :yikes: !

On the new injectors, shop around, you should be able to find a set for your car for much less :grinyes:
Probly around $300-350 for 6 injectors.

Good Luck

swingline
03-27-2007, 05:46 PM
ok, i got the injectors straightened out, watched pulse, all spray nicely.

front bank won't drop on injector balance test

ran compression test, rear bank decent, all three on front 50 or less

no coolant leaks, no oil in coolant or vice-versa, can hear it pop out intake and exhaust sometimes, especially during starting

my buddy and i suspect timing chain skipped a tooth(we are both mechanics, he more experienced than i) but why only one bank

any ideas?

swingline
03-27-2007, 05:49 PM
just to reiterate, very poor cold starting,

runs poorly in all conditions but driveable, under a good load it misfires to the point of stalling.

haven't done a cylinder leak test, but due to the noticable escape of air out of intake while starting and backfiring i'm quite sure its both valves.

razr_88
04-09-2007, 08:19 AM
hmmm if it's missing like you say you should get a code on the computer. try the paperclip trick real quick and make sure. not all faults show up on the service engine. (if you've already covered this, oh well)


try doing a vacuum test this will definitely show a faulty valve if you have one. (it's also very easy to do(in fact i have one installed so i can monitor the engine at all times in the cabin)) if your knowledgeable enough you could even determine whether the problem is the intake, exhaust, or even both valves. the needle says all of that

swingline
04-12-2007, 04:42 PM
i did the vacuum test, needle bounces all over the place. pretty sure it's both valves.

i replaced the timing chain and tensioner (the tensioner was so worn it fell apart) but I still have the miss. I think i might have burnt valves on the front bank (the injectors weren't firing properly and i was running lean) or possibly weak valve springs?

i have since replaced the injectors.

head gaskets are pretty spendy and I can't think of a way to be sure what's going on without pulling the heads and giving them the once over.

razr_88
04-13-2007, 08:05 AM
quite a few problem with the 3800.. what did you try jumping a train? j/k anyway you might be better off doing a complete overhaul. that would weedle out all of the problems. if you have the money, then would be the time to replace your valves, etc.etc

swingline
04-13-2007, 02:03 PM
i DID jump a train, do you think that's what caused the problem?

but seriously, i'm about to jump a goddamn train with this car. it's the devil incarnate.

i've thought about an overhaul, but i'd have to save up and i'd want to turbocharge it if i were to go that far.

thanks for the input.

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