rustbukt307

Hello everyone. I own a 1989 Cadillac Brougham that is equipped with a completely stock Oldsmobile 307 engine and the CCC Quadrajet carb model E4MC. I'm experiencing an issue where the vehicle stumbles and sputters when trying to accelerate and will stall when pushed hard enough. This originally began as an intermittent issue I would experience when the vehicle was warmed up and would occasionally stumble or sputter when passing or accelerating at part-throttle. I had first changed the fuel pump, then rebuilt the carburetor including all new gaskets and fuel filter under suspicion of flooding or starvation. I did not notice a change after the rebuild so I began to work on the ignition system. In doing so I replaced the ignition coil, ignition module, distributor cap, and rotor. Now after changing some parts the issue has become a constant and I've been held up for about two months trying to resolve it. I've checked the routing diagram under the hood to ensure the vacuum lines are connected and routed properly and found some of them to be in unusual places so I did my best to mimic the routing diagram apart from a few components not listed or not as they are described on the diagram. At this time everything is hooked up in a sensible way and there are no open vacuum lines or leaks that I have spotted.

I have a video here at "https://www.facebook.com/dopestar156/videos/10101464873324248/" of the car's current running condition covering idle and acceleration under load. I hear my car's engine and transmission are identical to what was offered in many RWD Oldsmobiles of the late 80s so I thought this would be a more knowledgeable place to seek help. Any of the Cadillac centered boards are baffled as there are only a few years where the Olds 307 engine was offered and most enthusiasts tend to go for the cars without this engine. I'd greatly appreciate anyone on here who can assist, I'm not in a place where I can have a disabled vehicle for too long without attracting some unwanted attention. Thanks and I'm hoping for the best.

shiftbyear

A vacuum gauge is a good tuning tool. Possibly clogged cat converter? Low battery voltage? No accelerator pump shot? Good luck

rustbukt307

Wow, the vacuum chart is very helpful already. I have a vac gauge I can check it with. Any suggestions on where to hook it up among the jungle of lines under the hood? I would be surprised if the problem was a clogged catalytic converter but I suppose I can look into removing it for inspection. I don't go for inspections anymore so I might just replace it with something less restrictive.

oldcutlass

You can hook it to any full manifold vacuum port. You can tell when a converter is clogged, you won't have much exhaust flow and the engine will run hot.

rustbukt307

The Cadillacs don't really have temp gauges so I can't really tell if it's running hotter than usual. If it is it isn't obvious to me. As far as exhaust flow goes I haven't really seen any evidence of that, but then again I've only been behind the car when it's idling. Flow seems normal at that condition.

Quadrajet Power

Did you replace the accelerator pump assembly when you replaced gaskets in the carb? That was mentioned above, that you may not be getting good pump shot.

rustbukt307

I did, yeah. It got all new parts from the rebuild kit too. I threw a vacuum gauge on it and it reads normal according to the chart posted by shiftbyear so I'm going to rule out a vacuum leak. The car now idles correctly but still getting that sputtering when under load. Noticed a bit of arcing from the distributor to the air cleaner. I removed all 8 wires then clicked them into place one by one. I don't see any more arcing off the air cleaner, but the sputtering condition remains. The cap, rotor, coil, and ignition module are all new. Maybe the ignition wires?

olds 307 and 403

Try new ignition wires and check/replace the plugs as well.

oldcutlass

Since you replaced the module, you may need to go through the timing procedure.

rustbukt307

Yeah, I was considering that next. I have a new set of wires but they're not the OEM style with the tabs that fit into that "crown" for the top of the distributor. I'm wondering if that matters for them staying secured.

I hadn't considered that. Do you think with all the new ignition parts the timing might have skipped?

shiftbyear

you may have nailed the problem. it's easy to check for arching at night or other dark conditions. To add to a previous check. you can check for a clogged/exhaust with the vacuum gauge. by revving the engine and holding at a fixed rpm, if the vacuum gradually drops you may have a clogged converter/exhaust. good post, good website.

rustbukt307

Thanks a lot, I'll give that clogged exhaust test a shot for sure. I've had a vacuum gauge for years and never knew how to really read it. Haha.

I suppose my next actions will be to replace the ignition wires and examine one of the plugs to see if they need to go also. Then I'll have my friend swing by with his timing light and check that for irregularities. Aside from a cracked cap or bad wires, would there be any other reason for arcing like that near the distributor?

My gut is telling me this is an ignition/spark issue and not a fuel one. I used to have an 84 Chevy K10 Scottsdale pickup with a 350 that had a bunch of bolt-on performance parts including long tube headers. Because of the design of the Chevy engine it puts the spark plugs right in between the exhaust manifold openings and I ended up with an ignition wire that would melt and arc off the header. The way the truck would sputter under acceleration was very similar to what I'm experiencing here only with a much less powerful engine so I would think the power loss would be much more significant. Plus the Chevy engine didn't have an ECM or any kind of emissions gadgetry to go nutty when it would do this.

rustbukt307

Okay..... new plugs and wires. No improvement. Got a Check Engine light for a code 44 while it was sputtering. Lean exhaust from the O2 sensor. Any indication of where to go from here?

Gary M

You may be back to looking for a fuel problem.

rustbukt307

That's what I was thinking. I noticed when I had the car in diag mode that the Mixture Control solenoid did not click at all. My FSM advises to check for a sticking M/C solenoid when a code 44 pops up. Against my will I might have to crack that carb open again. Does anyone know what the correct adjustment is for an M/C solenoid?

With a new fuel pump, rebuilt carb including accelerator pump, and new fuel filter, where else should I look for fuel related problems?

rustbukt307

Breaking news, I fixed it!

My original problem (which was intermittent) had to be the arcing ignition from either the partially melted cap or the aging wires, but my crippling death by throttle issue turned out to be a pinned down mixture control solenoid. A couple weeks ago when I cracked open my carb to check for a sticking float I misrouted the gasket that seals off the top of the carburetor. Instead of sliding it under the moving part of the M/C I had it going over top thereby pinning it down. I began to suspect the M/C when I didn't hear any clicking in diag mode and my car threw a code 44 which suggested to check for a sticky solenoid. I simply rerouted the gasket to it's proper place, reinstalled the carb, and voila. A perfectly functioning 307 and a Cadillac ready to hit the boulevards.

I wanna thank everyone on here for your helpful advice. I couldn't have come this far without your experience and knowledge and I learned a great deal about an engine I've been running for the past 13 years. Can't thank those who helped enough, going to be driving my Fleetwood for the next few weeks since I've got a lot of downtime to make up for.

gs72

Thanks for posting the fix. Some people forget and leave everyone hanging. Lol

oldcutlass

x2

rustbukt307

Yeah I try to remember my car forum etiquette. Haha.

Lesson to take away from this kids, mind your gasket placements and don't be too cool for directions.