I have a 1996 Bonneville SE with a 3.8 V6, which used to be my Grandmothers car. When I purchase the car it only had 29k miles. It now to this day only has 62K miles. Recently the water pump had gone out and I was trying to replace it myself. I am so glad that I found this form, because it has help me complete the task of replacing my water pump. I also replace the belt, which I couldn't believe that GM would make it so that you have to remove the motor mount just to get the belt off. I found that you could remove the spacer to the mount and slip the belt on without totally removing the mount as suggested in other post.

Ok now onto the question or should say problem. After replacing the water pump the car would start to miss after reaching warm up temp. 190F. Car would run fine when first started up. Now the car misses when you start the car and under heavy load like going up hill or open throttle. I replace the Crank Position Sensor, which was giving me a code error before. I have also check the Throttle Position Sensor, thanks to a previous thread on this form. It seems to be ok, smooth range .4v at idle and 4.1v at WOT. I went ahead and modified the TPS so that it would give me 4.28v at WOT. That was the best I could get out of it without having to drill the holes out to big. The computer has learned the new idle speed and seems to work. You can really see the difference in the way the pedal responses. But the car is still misfiring badly. Plug wires and spark plug wires have all been change out, new. Code that I am getting is a P0122 TPS/pedal position Sensor A Circuit Low Input and a P0300 Random/Multiple Cylinder Misfire Detected. I also tested the coils and all are reading at 5.1ohms.

I really don’t want to take it to a repair shop to get this fix. I can’t think of what else it could be, unless the TPS is bad. But I think the problem could be what ever gives it the voltage input first could be the problem. It also will not down shift at WOT. You really have to hit the pedal hard to get it to kick down. Help me guys.

Welcome to our group!

Could you retest your coils using the procedure in Techinfo?

http://www.bonnevilleclub.com/forum/...e=article&k=33

Those readings don't really fit with either the primary, which should be in tenths of an ohm, or the secondary, which should be in the thousands of ohms.

I'd think the TPS could be causing your WOT kick down problem, and maybe some idle concerns, but probably not the misfire codes. Check for vacuum leaks as a start, and we may want you to pull your plugs so that we can see what they look like. Also, read up on this techinfo article

http://www.bonnevilleclub.com/forum/...e=article&k=38

Let'* make sure that you aren't getting coolant into your cylinders.

Moving to 92-99 to get proper attention.

Here is the readings from the coils

coil / cyls Primary Secondary
1-4 1.0 5.45
2-5 1.0 5.46
3-6 1.0 5.33

Also I flush the coolant when I replace the water pump. Thanks for the info on the intake manifold. I get no white smoke from the tail pipe and I just replace the plugs with new Platimum (spelling) plugs. Old plugs look good with just a little of eletrode burn over.
I just wounder if it could be a coolant leak. Becuase I just had to add more coolant to the overflow tank again. It'* not much, but you would think that the coolant system would be full by now. It'* been about two to three months since I replace the water pump.

Try a pressure test on the cooling system. If it comes back okay, you've probably got a coolant leak in the lower intake gaskets.

With the coolant loss, I'd be quite concerned about an intake failure, either upper or lower. This is a recent post of a similar symptom with that as the cause. It'* a 2000, and supercharged, but still is a good example of the problem.

http://www.bonnevilleclub.com/forum/...ic.php?t=68369

If that it the case, it is not something you want to take your time about getting fixed.

I have the same problem with a 98 bonneville.... I punched the gas on the freeway to pass someone, all of a sudden my check engine light was flashing, and I had a little rough running. I got the car home and shut it off, and it would not start after that. I pulled the plugs and they had coolant on them. I pulled all the plugs, cranked it, and coolant came out. I removed the intakes, and the upper intake (top of lower) was an inch deep in coolant. The lower intake manifold gaskets were cracked up a little. I replaced all the gasked, replace plugs and wires, and reassembled. The car took a little to crank over, but ran for about 15 mins, and started displaying problems again, so I shut it off. The car would not start again. I pulled the upper intake again and there is coolant in there. I did not notice and cracks or anything, and was very throrough about checking everything... any ideas?

Thanks!

Ray

It may help out Dad'* Toy, too. Check where the EGR stovepipe comes up through the upper. You may find that the plastic has crumbled, and broken through into the coolant passages. Poke at things with a sharp object, even if it looks solid. Read techinfo article 38 posted above for recommended replacements.

Man I can't express how much I enjoy all this feedback and info. Thanks.Archon for the additional threads. It lead to much more info than I was able to get from the search engine on the form.

I have notice that my oil gets discolored very fast after just changing the oil. I ony drive the car to & from work which is about 15 miles around trip. It shouldn't get that drity that quick. I have no signs of coolant on the spark plugs. I did upgrade them yesterday to double platium plugs. Did a resistance test on the plug wires and found two that are in question. Plug wires are NXT wires and have a lifetime warranty. So will be replacing them tonight.

I am very concerned about the coolant LIM/UIM problem that some of the 3800II motors have. Just woundering if it would be necessary to go ahead and replace the UIM with the kit from APN. They seem to have the solution which comes with all the parts and instruction. Or would it be just cost savings to replace the gaskets only.

On those Bosch Double Plat'* you just put in.

Bosch Plats have never seemed to hold up well in our cars and a recent thread identified it as an issue with a waste spark setup. (Our cars fire both posts on each coil at the same time)

Bosch themselves had information mentioning that this waste spark degraded their product prematurely and recommended not using their product in the waste spark applications.