Codes

I have no info on either code.

IS there a perfornmance problem or service enginne soon light problem, that made you pull the codes?

yes the motor runs very ruff when trans. is put into any gear. I found a short description of the code p0640 from the scan tool that I used from a tool seller I know. It was somthing about the quad 4 system. The hookup for this car has a 16pin connector that a obd2 scanner will plug into but will not read. that's when I looked under the hood and found that it's obd1 certified. It seems that the ruff running only happens when the rpm,s are low. I am a deseil mecanic and have been for ten years. I rebuild engines and know engine management systems. But in the hanyes manual there is know mention of these codes or the quad 4 in the scumatics for the pcm.

ahhhhh. p1640 (illuminates mil light) and p1670 ( does not illuminate light).

That's quad driver circuit. Likley ground problem or moreso a pcm.

The Quad driver is hard wired in to the PCM. To check the drivers, in your case #1 and #3, you need a scan tool to command the driver switch to energize (ground) the circuit while checking with a test light. Alos you need to operate the vehicle in a way that should cause the suspected portion of the driver to switch “on”. There may be circuit breakers that failed to protect the module.

where might these quad drivers be located and what purpose do they serve? The pcm is the GM factory unit.

A quad driver is a component that has four outputs that is controls. IT is part of the PCM, not serviced separatly, it is available aftermarket. You need to pull the pcm and get the part number off of it.

O.K i got the pcm out it's right here in front of me but i'm not sure which # is the part # . Also do you know of any good aftermarket companys to get one of these. Alright here are the #'s

serv.no. 16183247

86bmyum643127udd

16211694

bmyu

That's how it looks on the label??
Thanks for all your help it means alot
If you know which is the part # let me know.
Oh and by the way i bought a preaty nice scan tool that does live data and the engine has missfiring cylinders 2,4,6 on and off not all the time.

brian

Hi Brian,

16183247 is the number the parts store will need. Napa would probably be my choice of suppliers on this. I think they have a-1 cardone as the manufacturer. Advance auto may also carry the same.
Aside from a-1 cardone, Standard ecms have been pretty good also. You may also have luck out of a junk yard if the cost is unreasonable. I would guess a hundred bucks or so.

thank you for all the help you have been!

Brian

Don't thank me until the problem is solved :shock:

Before doing anything else, check behind the glove box for blown fuse(s).

After a little looking around, I learned that the first quad driver controls the boost control and purge solenoids and the tcc soleniods. While I have run into a computer issue on these, research is showing that is is more likely a problem on one on these circuits. The fact that the # 3 quad driver is also a problem may indicate 2 problems or more.

The misfires are a concern to me. These had a problem with the intake manifolds and I wonder if there is an internal leak there.

I found the problem with the quad 4 system. The place you told me to look for those fuses, I found the 15amp fuse was blown. Ialso found what caused it. the a/c compressers clutch was locked up an the coil that makes the clutch engage melted togther do to the heat from the bearings and created a dead short. If your wondering the a/c compressor has been bypassed with belt designed for engine without a/c.Also the motor still is running ruff. I spryed starting fluid around intake manifold and vacum lines plus throttlebody found nothing. Then when it was dark I started spraying water around sparkplug wires and the ones that where missfiring on and off, you could see the wires arcing togther all over. I,m going to change plugs and wires tomorrow. I hope this is the only problem. It also serges when throttle is held in one spot do you think those spark plug wires could cause this??

Good chance on solving the misfire with the wires. IF they are arcing, they are misfiring.

Well changed the wires and plugs still doing the same thing. Cylinders 2 4 6 all rear head cylinders. Now I have two more codes since I let the motor warm up. One is p0300 multipule missfire and p0406 liner egr pintle position error. Plus when I look at live data on my scan tool it shows no change in position of egr at all even when I rev motor all other sensors inticate change when rpm's change. Is it posible that the egr valve could be causing these problems. The engine serging when throttle is held in one positon and these mutiple missfires??

I have a 95 Buick LeSabre and I recently had a new harmonic balancer( whatever that is) put in but now it is making up the same noise it was making before I put it in there! What should I do?

Krystal

Well the plugs and wires were still good to do, the multiple misfire is just a regurgitation of the misfires on the 3 cylinders suspect. PO406??? Are you startin that again!!??

P1406…now that I have you patterned!

Hate to say it is leading down that bad PCM path again, but not to say the egr valve is not the problem. You could try cleaning it for starters. If it doesn’t work, post back and we’ll go from there. Krystal, Start ne new post, Thanks.

I pulled the egr valve off and cleaned bottom and pindle very well with brake clean. The pindle was moving very well with my finger before i cleaned. But I got all the gunk off. Do you think that egr vale could cause Those missfires and serging?? I have seen egr vales cause the fuel pump to shut down in a caviler. Well I should of worded that properly the pcm wouldn't tern on the fuel pump because of the egr valve. I have also seen egr valve make an engine overheat. Well here is something I thought you might like to know cat and detroit are starting to use egr vales and egr coolers. These big deseil engines are starting to get tested and have to pass smog tests and can't even build the engine unless it is going to pass an emissions type of test. I never thought I would see egr valves on a big deseil engine but the ozone is getting messed up and trucks is one of the top causes. well let me know what your opinon is on this egr vave and these symtoms. Ohh by the way I herd that it's posible to get coolant in your oil because of an upper intake. Does coolant run though the upper intake manfold, the only place I know of is coolant going though the throtle body?? Well let me know I typing your eyes off!!!

Thanks for all your help!!!!!!

brian p.

I believe there is a coolant port on the passenger side. And if I recall right, the manifold's design allows coolant to erode and over heat the manifold right there. Are you losing coolant?

Might want to pull those plugs and get a look at them for any tell-tale signs.


I'm not surprized the big trucks are going in that direction...world's getting to be a scary place to live in.

I cleaned the egr vale and the code went away. I am sorry you miss understood what i was saying in my last post. I am not not the one havimg the problem with the uper intake manifold. I was just asking you if you thought it was possible to get coolant in oil from cracked upper intake. Well anyway back to the buick it only has the one code now multiple missfire. But I found out some new info on this car. When that belt broke because of the a/c clutch the motor overheated. So I am wondering because all the cylinders that are missfiring are in the back head. But when I had my scan tool hooked up I was reving the engine looking at the live data and I noticed that the injector pulsewith would drop way down sometimes to zero when the motor starts to serge from being reved. I was also thinking about the prom chip in the pcm might be bad. Please let me know what you think about this new info.

With the misfires all being on one head, we need to determine what they all have in common, and which element is likely dropping out between fuel compression or spark.

I would check compression on the three cylinders to at least eliminate a compression problem.

How bad is the misfiring? Does it affect the runnibility/drivability or is it very subtle and inconsistent?

Check the coil towers and make sure there is no corrosion on the wire or coil post.

Maybe it is just ironic that the misfiring is just on the one head, but I expect a relationship....between the head and misfirng that is....not between us :shock: :lol:

The missfiring is very bad once the car is put into drive. Even at low rpm it is horrible!! When your in gear and try to accelerate it pretty much falls on it's face and takes awile to get up to speed. It's like it loses all three of those cylinders all together. Then once the car gets up to speed it's not to bad. It's like when you put a heavy demand on the engine it dies so to speak. The car does not have tags on it yet so yesterday was the first day I realy took it for a small road test. I will do compression test and let you know. What I was saying about the injector pulsewith was that it was dropping down to zero when the motor serged when the fuel pedel was held in a steady position about half throttle. The motors rpm goes up and down very fast and it's very bad!! But idels pretty good.

I know I give horrible descriptions but am having a hard time putting into words.

Brian

Found the problem cylinders 2,4,6 which is the back head had 150 psi reading give or take 10 or 15 pounds. But the funney thing is the front head which is the head that was not showing the missfiring was the head with out compression. Cylinder 1 read nothing cylinder 5 read 20 psi and cylinder 3 read 50 psi.


Thanks for everything

Brian p

if your going to pull the head, send it out to a machine shop for testing and surfacing. Best way is to do both heads.......assuming it is the head :shock:

I pulled both heads and had them checked, both where fine. found that on the frount head the head gasket was blowen between all three cylinders replaced both gaskets put back togther. Now the motor has real good power on take off and sounds good idealing but still serges when throttle is held in one spot. Also still runs ruff when put into any gear. It seams to be related to the low rpms because soon as you push the throttle even a little it starts run o.k.


This car really starting to bug me!!!!!