issues with 3800 V6

[Cleveland Dave]

92 Buick Regal GS
185k

for the last 3 weeks my buick has been intermittently running poorly. during acceleration it would hesitate and act like it was misfiring, however this was only on occasion most of the time it was fine. well friday night i was driving it and it stalled out at about 55mph. after about 4x trying to get it started it finnally went but now it was having serious acceleration problems, idling very badly, and stalling out when coming to a stop or if i pressed the accelerator down too much. i made it to my friends house and after letting it sit for a few hours i could not get it started. next day i tried again and after about 15 minutes it started and kept running, i was able to drive it to my parents house 15 miles away where i could have my dad look at it. we noticed one of the ignition coils was sparking so i replaced it. however still same problems. not able to get it started, when it does start it will idle very rough, and have lots of problems with accelerating. so today i decided to changed the spark plugs because they havent been changed for 75k miles. got all of the spark plugs changed. after 3 attempts the car kept running and i was able to drive it around the block without it stalling, but under acceleration if i tried to push it down more it would act like the car was going to die.

any ideas?

from searching the web i found that it could be a dirty throttle body, misaligned TPS, or possibly a bad crankshaft position sensor or possibly a number of other things

what do you guys think?

[PureSound15]

Maf?

[Cleveland Dave]

hmm good suggestion ill have to look at that tonight, thanks

[PB86MCSS]

Setting any codes? I'd check fuel pressure too with key on-ignition off then running just to rule the fuel system out too.

Sounds like an ignition problem, that would be the most common over TPS, MAF or IAC, IMO :D . Check the car running at night or in the dark for any random sparking or arcing? I'd bet one of the coils or the ignition module from the sound of it. I upgraded my LeSabre to the Delco II ignition (same as your Regal) and have some spare coils and modules in my car with tools just in case. Overprepared or paranoid I know but those would probably be the first things to go. Not common I'd say but I'd start there first. Modules can be tested at auto parts stores, not sure on coils.

[team beater]

lower intake manifold gasket

[team beater]

they are a common problem with the 3800's, sounds like this maybe your issue.

[spooln30]

Unplug the Maf and if it runs better that's your problem. Just make sure your have a 5 volt reference and a 12 volt power supply at the connector. If you have the correct voltage then replace the MAF. I would lean toward the MAF being the problem.

Keith

[stenchmiester]

Does this have an ecm under the coils. If so check that out.

[Coops Brother]

Check the plug wires at the plugs, as I recall they have aluminum sleeves over the boots that tend to arch out and is hard to see. Also check for a plugged fuel filter.

[Cleveland Dave]

Unplug the Maf and if it runs better that's your problem. Just make sure your have a 5 volt reference and a 12 volt power supply at the connector. If you have the correct voltage then replace the MAF. I would lean toward the MAF being the problem.

Keith

i unplugged and also checked the maf, the screen didnt seem to be plugged up or very dirty. when i unplugged it, made no difference in how it ran.

after replacing the spark plugs it seems to start easier but i did have to give it some gas to keep it going, once its been running it seems to stay running now but as soon as i press on the gas more then just a little bit it hesitates and bogs down like its going to die.

[Cleveland Dave]

Setting any codes? I'd check fuel pressure too with key on-ignition off then running just to rule the fuel system out too.

Sounds like an ignition problem, that would be the most common over TPS, MAF or IAC, IMO :D . Check the car running at night or in the dark for any random sparking or arcing? I'd bet one of the coils or the ignition module from the sound of it. I upgraded my LeSabre to the Delco II ignition (same as your Regal) and have some spare coils and modules in my car with tools just in case. Overprepared or paranoid I know but those would probably be the first things to go. Not common I'd say but I'd start there first. Modules can be tested at auto parts stores, not sure on coils.

no engine codes. i replaced one of the coils that we noticed was sparking.
after replacing we havent noticed any sparking or arcing.

[spooln30]

With the amount of miles you may have a faulty or clogged IAC. If you unplug the IAC does it make a difference in how it runs? Any codes? If you have access to a scan tool you can perform tests. Like to adjust the IAC open and close %. I'm sure it's something simple. GL. Keep us updated.

Keith

[spooln30]

I see you just posted no codes. Another thing to check is the data for the TPS. At idle it should be about .70 volts IIRC. Then KOEO do a WOT the voltage should read 3.8-4.7 volts. I can't remember what the max volts is. Then let off the gas and slowly press the petal checking that the voltage goes up smoothly and doesn't jump up. If it checks out it's good.

[spooln30]

Oh I forgot to tell you to pull the vacuum hose off the FPR to check for a fuel leak. It could be the FPR also. Just have to check everything one by one. I've have older GM's with simular running conditions have bad FPR.
It kinda makes since that when you did a tune up it ran a little better. What happens with a leaking FPR, the engine under vac will suck that extra from the FPR into the intake system causing a rich condition. Meaning your old plugs were probably fouled out from too much gas.

[Cleveland Dave]

thanks ill have to check it out more tmw. its at my parents house about 30 miles away from where i live.

[Moparjim]

I too have had the FPR issue with those as described. Doesnt throw any codes but exhibits symptoms you describe.

[brotherbenn83]

A leaking fuel regulator could give you those symptoms at idle from too much gas, but not off idle as the spare gas would be needed with increase throttle request. Did you check/change the fuel filter? I would check your fuel pressure and make sure it isn't really low from a restricted filter or weak pump, then I would I would check the ECT reading with a scan tool to make sure it is reading correct to make sure the ECM is giving you proper fuel for actual temp (i.e. there would be tooooo much gas dumped if it thinks the coolant temp is -40) Also I have seen faulty position 1 oxygen sensor cause an improper fuel mixture if they are skewed, you could check this the same way you did with your MAF; unplug the connector and see if it runs better (the O2 sensor is straight up in the rear manifold) if everything here checks out, check for a plugged catalytic converter, or a possible bad crank position sensor.
Good luck.

Ben

[Al]

I had the EXACT symptoms on my 89 Olds.

It could be the ignition control module. When mine went bad, the CEL came on and it intermitently hesitated. Most noticeably, the engine stalled at stops. These are $70-100 and easy to replace.


[CODE 41]
http://www.brewcitymuscle.com/forum/showthread.php?t=48157
It could also be your cam postion sensor magnet. These are more likely to go than crank sensors. The crank sensor relies on a disk on the crank with slots cut in it. As for the cam position sensor, it relies on a magnet in the cam sprocket. The sensors tend to be reliable, but the magnet has a bad habit of falling out of place.

Fortunately, the cam magnet is only $7. Unfortunately, you have to remove the cam sprocket to get to it. BUT, there is an alternative method for replacing the magnet. This involves pulling the cam sensor out, pulling out the old magnet (or what is left of it), and JB welding a new one in.
http://bellsouthpwp.net/p/a/padgett46/cammag.htm
I did this and it has held up for 5000 miles.

[PB86MCSS]

Curious if there has been any progress myself...still betting on coil/module, probably the easiest thing too although new parts are pricey. I'd grab multiples from a junkyard instead personally.

[Al]

Curious if there has been any progress myself...still betting on coil/module, probably the easiest thing too although new parts are pricey. I'd grab multiples from a junkyard instead personally.

You can use a multimeter to check the coil.

[Cleveland Dave]

im waiting to get it to a shop somewhere....im not really much of a mechanic, i can do simple things but im kinda lost when it comes to this stuff. figure it would be better too for them to run there diagnostic tools and figure out what the issue is.

ill keep ya guys posted thanks for the suggestions.

[PB86MCSS]

Just curious, any update?

[BadAzzGTA89]

I venture to say IAC.

[Cleveland Dave]

Just curious, any update?

not yet, still sitting at my parents house. im trying to get caught up on some bills and stuff so i should have money to get it fixed in the next week or so. then ill get it to the shop and see what they say.

[Cleveland Dave]

so its in the shop so far they have found that the fuel pressure is low. its at 10# and should be at 30#.

[Cleveland Dave]

talked to the mechanic.

The mass air flow was changed and the readings are great now.

Except it doesn’t run right. Low fuel pressure.

I called and mentioned the fuel pressure regulator and he said they rarely fail and when they do the diaphragm tears and gas blows into the vacuum tube spewing out.

The regulator checks out fine.

$400 for labor and parts to drop gas tank and replace fuel pump.

They are checking the fuel filter cause it will cause the same symptoms. Usually replaced before 100K on most cars due to bad gas at pumps.

He said the tie rod in front (causing bad tire) is about ready to fall off $300-400.

The rear tie rods are going.

[PB86MCSS]

Ahh. Not sure if you have a pressure tester but that would of been one of the first things to check given the symptoms. Glad you updated us though, I almost forgot about this one. Given the age/mileage the pump lived it's useful life and then some I'd say. Mine was replaced before I got the car, with just under 100k and 7 years ago or so, IIRC.