PontiacBonnevilleClub.com

Hey,

So my great aunt gave me her old Bonneville and for a time it was running just great. Up until about a week ago when it would give me some trouble starting up. I've lived with crappy cars my whole life, so I didn't think much of it.

On the way home from class, it chugged going up a hill and then died in the parking lot of my apartment complex when I took a sharp turn.

Here's what I know.

It's turning over and has a brand new battery.
Motor sounds like it's running fast enough for air.
I can hear the fuel pump running.
Has several gallons of gas currently in the tank.
It chugs and tries to start, but doesn't seem to have either the spark or the fuel to get the motor fully running.
Checked fuses and relays, those are fine.

My dad's been passing me info over the email (as he knows much more about cars than I do) and I've done what I can with limited tools and knowledge myself. He thinks it's a bad coil or possibly the timing chain (I hope that's what they're called).

Anyone have any other ideas about what it could be, or ways to check said problems myself? I really want to know if I can't fix it myself or at least know what the problem is before I get it towed to a repair shop (I'm a poor college student, I want to avoid any expense if possible).

Much appreciated!

Where are you located? We may have some members in your area that can help out with the diagnostics.

The only question I can think of off the top of my head is "can you smell gas coming out of the exhaust?"

You'll want to check for fuel and spark.

For fuel, you can put a 194 type bulb into the each fuel injector connector if you remove it from the injector. You only need one, you don't need to do all six at the same time. It wouldn't hurt to try each one individually. Have someone crank the engine while you look for the bulb lighting up.

You can also borrow/rent a fuel pressure tester from most parts stores like Autozone. I forget the specs for an 88 though. If it's been ages since the fuel filter was replaced... it might be a good time to do it now.

For spark, you can try this: Remove one spark plug at at time, put the plug back into the plug wire boot, and hold the threads firmly against the block (holding it by the plug boot), head, exhaust manifolds, or one of the engine lifting eyes/grounding posts. Have someone crank the engine while you look for spark. Remember, there's a decent amount of voltage, so don't touch the end yourself or get real close to it.

I'm located in the Dallas area.

I'll see what I can do about testing spark plugs and such.

It could be a faulty crank sensor, Cam sensor or a bad Ignition Control module, if the crank sensor is faulty or has a bad ground then it will not send a signal to the PCM to fire the cylinders (crank but no spark condition) the cam sensor is also linked to controlling spark and fuel.

Several things to check, but you'll need some tools to do it.

Fuel pressure is first, spark is second, then a good scan tool that you can use to check each one of the sensors to see if you are missing a signal. If you've never done this before, then taking it to a shop may be the quickest way to get it up and running again.

Some known problems with this version of the Bonnie is the ECM (brain box under dash on the passenger side) and the Coil Pack on the engine. Car is over 20 years old and has a lot of electrical connectors. Re-seating all the connectors can sometimes correct mysterious problems and costs nothing but your own time.

Another common problem is with the vac fittings & lines. They get hard and brittle with age. A cracked vacuum line or fitting can lead to a major leak of air into the motor, making it hard to start and a poor idle.

So, how are you fixed for tools?

I myself, and multiple family members have had that style 3800 motors, and my best guess is a ignition coil from what you say. I agree with all these other posts, about checking all the info, but from my personal expirience, if it cranks and "sputters" like it wants to start, I would say ignition coil. I have seen 6-7 of those magnavox coils go bad, and they have all made the car sputter during cranking without starting. Best of luck!

An 88 bonneville is a good solid car though. if the rest of the car is in good shape, its certainly worth fixing!

You can swap the coils and ICM from a newer 3800 on to your car. Cheap, easy, and it's more reliable.

clm2112 wrote:Several things to check, but you'll need some tools to do it.

Fuel pressure is first, spark is second, then a good scan tool that you can use to check each one of the sensors to see if you are missing a signal. If you've never done this before, then taking it to a shop may be the quickest way to get it up and running again.

Some known problems with this version of the Bonnie is the ECM (brain box under dash on the passenger side) and the Coil Pack on the engine. Car is over 20 years old and has a lot of electrical connectors. Re-seating all the connectors can sometimes correct mysterious problems and costs nothing but your own time.

Another common problem is with the vac fittings & lines. They get hard and brittle with age. A cracked vacuum line or fitting can lead to a major leak of air into the motor, making it hard to start and a poor idle.

So, how are you fixed for tools?

If the "brain box" is the box next to the secondary fuse box under the glovebox...I reseated all those connectors already.

I've got a decent socket wrench set and some basic pliers, etc. Nothing fancy.

newtongtz wrote:I myself, and multiple family members have had that style 3800 motors, and my best guess is a ignition coil from what you say. I agree with all these other posts, about checking all the info, but from my personal expirience, if it cranks and "sputters" like it wants to start, I would say ignition coil. I have seen 6-7 of those magnavox coils go bad, and they have all made the car sputter during cranking without starting. Best of luck!

An 88 bonneville is a good solid car though. if the rest of the car is in good shape, its certainly worth fixing!

Lets assume it is the coil...what would be the easiest/cheapest way to test that? It may have been said earlier, I'll re-read posts.


Thanks again for all the help, it's likely that I can't fix it myself but knowing what to tell a mechanic will help.

Most local auto parts stores can test your coil for free... to take it off I believe its 6 torx bolts (I don't remember the size torx) Pull all the spark plug wires off, and disconnect all the wires underneath the coil. (be careful doing this as you don't want to snap off any of the tabs) and your done... just take it into the auto parts store for testing. If it is bad, they will prolly try to sell you a $100 new one, but if your just looking for "cheap" I would go to the local junk yard and pick up another one for $20...

oh yeah.. be careful not to put the spark plug wires on backwards for re-install...

Also, you can take your ignition module in for testing too. that is right underneath the coil, and is held on by 3 bolts on the bottom side, and one wire harness held on with 1 bolt.

If one of those 2 things are the "issue", I have a known working ignition coil and module together that you could have for the price of shipping... Its just sitting in my garage. It came off a 90 olds 98 that I no longer have.

Best of luck!

Like I said, check with local yards and see if they have a newer ICM and three coils. Might cost you $30, and will be a far superior setup.

00Beast wrote:Like I said, check with local yards and see if they have a newer ICM and three coils. Might cost you $30, and will be a far superior setup.

I agree 100%! That would be why I have a extra icm and coil just sitting in my garage collecting dust.

The junk yard up here only charged like $18 for the whole setup as long as I pulled it myself. Well worth it, but the yards around here are the cheapest I have seen anywhere, so He is probably right saying $30...

But, we're getting ahead of ourselves. Before he goes spending $$$ on parts, he needs to make sure that's the issue.

You are going to need a 2nd person to help you out (to turn the key for you.)

Checking spark can be done with a regular timing light (doesn't need to be a fancy one, a simple one with an inductive pickup will do.) If it flashes, then you are getting spark.

Typically, if you have a problem with the ignition system, there will be a strong smell of gasoline after repeated attempts to start the car (all the fuel that got dumped into the cylinders will just be laying there.) Also, while trying to start the car, the sound of the starter will remain the same or slow down as raw fuel collects in the cylinders.

To check fuel, you need a pressure gauge. There's a fitting on the plumbing that connects all the injectors that looks like an valve stem on the tires. With the ignition switch on and the pump running, you should see about 40psi. It should stay at that pressure while cranking the engine. If it drops like a rock or never gets over 20 psi, then you probably have a plugged up fuel filter under the car. You can test the injectors with a light bulb as described in a previous post.

Symptoms of no fuel/low fuel pressure is like the motor speeds up and pops occasionally when trying to start it. It might even run for a second or two at a time before dying. The surges come from the little bit of fuel that is getting into the cylinders. When enough raw gas collects and lights off, the starter will speed up briefly.

Check the air filter too. If it is really plugged up, it can make it hard to start the car. Even plugged up, the air filter alone usually doesn't prevent the motor from running. But it is easy to eliminate and let the engine breath as much air as it wants so you can track down the real problem.

Last bit of advice, don't run the starter for more than a few seconds at a time. If the car doesn't start, then give the starter motor a minute to cool off between attempts. No sense burning up the starter while figuring out what is really going wrong.

newtongtz wrote:Most local auto parts stores can test your coil for free...

Don't waste your time. I've seen good ICM's test bad and bad ones test good. Auto parts store testers are very limited and basic. They cannot simulate what the coils or ICM are going through under load installed on the car.

As a quick update (busy with homework, very little time to work on car)...I don't smell gas after failed starts. I believe someone asked about that.

Talked to my dad...

Lets replace the ignition coil/module and see how that works.

With my limited tools/knowledge, would it be doable myself? As I said earlier, really busy with schoolwork now (10 page paper due soon, reading the Odyssey and a speech due soon, woo)...but by this weekend maybe I can get my hands on a new coil/ICM.

The apartment complex I live at has a "no working on cars" rule, but if I can get in and out in 30 minutes or so, I can probably get away with it (and hey, I pay my rent on time and I won't be spilling fluids everywhere, they should cut me some slack).

Coils and ICM are super easy. Take the bolts of holding the coil pack down, and if I remember right, there's nothing else holding the ICM down. From there, there's a bolt holding the wiring connector on.

newtongtz wrote:Most local auto parts stores can test your coil for free... to take it off I believe its 6 torx bolts (I don't remember the size torx) Pull all the spark plug wires off, and disconnect all the wires underneath the coil. (be careful doing this as you don't want to snap off any of the tabs) and your done... just take it into the auto parts store for testing. If it is bad, they will prolly try to sell you a $100 new one, but if your just looking for "cheap" I would go to the local junk yard and pick up another one for $20...

oh yeah.. be careful not to put the spark plug wires on backwards for re-install...

Also, you can take your ignition module in for testing too. that is right underneath the coil, and is held on by 3 bolts on the bottom side, and one wire harness held on with 1 bolt.

If one of those 2 things are the "issue", I have a known working ignition coil and module together that you could have for the price of shipping... Its just sitting in my garage. It came off a 90 olds 98 that I no longer have.

Best of luck!

The Coil is held to the icm by 6 torx head bolts, and the icm is mounted to bracket off the engine by 3 nuts on the bottom side and 1 wire harness held on with 1 bolt...

you should have no problems what so ever getting them both switched out in 30 min.

willwren wrote:

newtongtz wrote:Most local auto parts stores can test your coil for free...

Don't waste your time. I've seen good ICM's test bad and bad ones test good. Auto parts store testers are very limited and basic. They cannot simulate what the coils or ICM are going through under load installed on the car.

I'd like to re-state this for clarification. Don't bother having coils or an ICM tested at any auto parts store. I've seen this go bad too many times over the years, and not just in my time on this Forum since 2002.