five7kid

iTrader: (14)

Original post here https://www.thirdgen.org/techbb2/sho...ighlight=sense . '90 Bonneville SSE, won't start when cold over night, floods when attempt to start cold, etc.

I've been out of town since Feb 12, was home weekend before last. One injector leaking at fuel rail, pinched o-ring (yes, I did oil them before install), fixed that, set TPS voltage to .54VDC (was .47), started right up. But, temp was above 45 degrees then. Started fine throughout weekend (very warm, 75 degree Saturday, snowed Sunday night, still started okay Monday morning). I go out of town again Monday morning.

Tuesday morning, cold out, below 20 degrees, about 35 in garage - wouldn't start. Flooded. Could get it to start after a lot of cranking and flooring, would start fine rest of day until it sat all night again.

Wife takes to dealer last night, leaves it outside. They look at it this morning, wouldn't start for them. Tech puts "known good" coil pack and ignition module on, starts right up (so they say). They want to have it overnight again so they can check it in the morning again. Estimated repair cost: $500.

What they said is a bad coil and ignition module would cause no injector pulse and a weak spark.

Now, I may not be the brightest bulb in the pack, but:

How can this only happen when below 45 degrees?
How does bad ignition module cause no injector pulse?
How does no injector pulse flood the engine?

Oh, answers to questions in last post:
PROM ID 8034. (As for SBs mentioned, how could PROM load go this long and suddenly cause a cold start problem?)
Have Auto X-ray, no trouble codes throughout this adventure (but then, bad crank trigger last year didn't set a code, either). No gear selection anomalies. No TCC problems at all. Before starting, coolant and air inlet temps agreed very well to garage air temp.
New plugs (and wires) put in in January, no difference.

Any insight appreciated.

five7kid

iTrader: (14)

It didn't get that cold last night, only about 35 degrees, we'll see what they say when they look at it.

Vader

5-7,

A possible explanation (a.k.a., another dumb guy's guess):

Internal ignition coil arcing between the coil primary and secondary windings can be very difficult to trace. Checking for internal arcing requires an engine analyzer/scope, and as long as the primary current is switched normally, there may not even be a misfire DTC set for a given cylinder. The older ECM in your '90 might not even track misfires, but the Buick V-6s got the improved PCMs before anything else. I'm just not sure what year that was.

There were several TSBs on the coil packs on the V-6 engines, but I don't reacll all the listed symptoms. An epoxy filled coil can fail from thermal expansion/contraction of the solid insulation, and lack of spark would certainly load the cylinders with fuel. As the engine is cranked, the coil primaries would still be switched on/off. this would potentially heat them from the currrent flow (exactly the reason the ignition shouldn't be left ON without the engine running for extended periods). This coil heating could "grow" the insulation back to a size that would move the secondary windings enough to eliminate the short, allowing a spark to be generated.

They always said the coil packs were problematic on these engines, and they certainly didn't help with the placement of them (right between the fuel runners).

Just a possibility.


BTW - You must have had the gold plated replacement coil packs ($500.00?).

Vader

5-7,

And not to keep shooting at a dead horse, but didn't I mention coil packs in a reply in that first thread (#17)?

I've only had experience with one of these engines in a relative's car, but in researching the problems it had I was thoroughly unimpressed with the ignition system - still am.

I'd still be concerned about the EPROM and CalPak TSB, and for about $50.00 you can get a replacement and be sure you don't have the "bugged" one.

Just another 2¢ from the Dark Side...

five7kid

iTrader: (14)

The coil pack and ignition control module on the '89-'92 3800 are on the right/front of the engine (to the left as you're standing looking at the engine). I had an '89 with 170k miles on it before it was totalled, same engine/ignition, never once had a problem like this (except ECM died at 120k). When I was trying to figure out what turned out to be the crank trigger last year (would die when hot in that case), a GM tech who responded to my question here made the statement that those parts are often changed when they in fact seldom fail.

I still don't understand the "no injector pulse" part - how does it flood with no pulses?

From PartsAmerica.com, the ignition control module and coil pack are about $210 for non-Delco parts, $260 for AC-Delco, so one can imagine what they'd be from the dealer. They're charging $88 for diagnostics. I would guess if they were charging their shop hourly rate, it would be more than $500 for the parts and actual time they've spent on it. Not that I'm thrilled to be spending $500, mind you, I just want this thing to start reliably, and I do NOT like to be in the parts-changing-to-diagnose mode, especially when I can't put them back on the shelf when it's not what's wrong.

five7kid

iTrader: (14)

Oh, you posted again before I did...

Yes, you mentioned the ignition. One typically thinks of failure when hot when those parts are involved, though. We drove it round-trip from Colorado to Montana beginning of February, only problem it gave us was trying to start it in the morning. I understand a circuit could also be broken from contraction when cold, but that is rarely the case, in my experience (of course, that may be hard to know for sure, because if the circuit is open when cold, how are you going to get it started so it closes when hot?).

five7kid

iTrader: (14)

Just talked to the dealer. They're confident it is the ignition module & coil. Didn't explain the "no pulse = flooding" to me, but...

It's not $500, either. The actual retail price is...

$685! Lifetime nationwide parts & labor warranty.

Oh, I didn't include the price for the gasket that goes between them, either. I'm sure that made a difference.

Vader

5-7,

Gotcha so far. I'm just theorizing, since I'm scanning the diagrams I have available and can't find a G#DD@XN muthr-%&#k'n THING that's very clear on this system.

I'm guessing that since injector pulses and ignition are being timed by the position sensor, and that both have some interdependency due to the VATS, there may be some signal "noise" or signal suppression caused by the random higher-voltage spikes generated by the ignition coil (being shorted primary to secondary). Any noise or suppression of the signal may force the output transistors for the injectors to bias forward and remain on, and/or totally screw the ignition module, rendering it unable to switch priomary current to the correct coil pack(s) at the correct time. I'm guessing that while you were getting spark during all this cranking, it may not have been in the right hole at the right time. Once the spark plugs were wet with fuel, the subsequent sparks were grounded through the wet insulators on opposite cylinders instead of bridging the gap - at least until the cranking in "Clear Flood" mode got enough air through the chambers to dry them a bit.

Granted, this is all purely speculative, and I'm by no means an expert. If you haven't done so, you may want to talk directly with the technician instead of the service manger. You may get a more educated explanation of the condition from the person that diagnosed it. If that doesn't get you a good explanation, you might want to try GMTech's email link. I'm fairly certain he has/has dealt with one of these in the past and is excellent at diagnosis and explanation.

five7kid

iTrader: (14)

Sounds reasonable. Except no VATS. I wondered about the "spark getting there are the right time" scenario myself.

Although I didn't talk to the tech himself, the service manager specifically said the ignition was causing a no injector pulse condition.

Time will tell if they got it right.