dleefsu

Hello - I'm going to do the paid member when get home tonight but trying to fire this off before work. My 964 has always run great but in the past 2 years didn't drive it much during a major renovation. Tried to run it at least once a month give or take. Recently went to run it, started fine but ran a tiny bit rough but not alarming, could say as good as could expect not running regularly for a while. Took it for a spin and no issue. Made a stop and when went to start it, didn't instantly start which was odd. Had to work with it a bit to get her to start but once did, idled OK, a little rough but usually as smooth as can be so little rough still wasn't bad. Let it idle for a little bit but when went to drive it started running pretty rough to then quickly progress to backfiring and misfiring. I was very close to home so was able to get her home.

Once home she was blowing some smoke but not sure if it was from combustion or some oil burning off. There was definitely some burn off, just not sure if there was smoke from combustion. Called it a day and next day or so she definitely started blowing smoke but usually just after ran a few minutes (idling). With such issues didn't want to do any crazy revving. At this point a few times started her over perhaps the course of a week and sometimes seemed to run good/ok, other times not, still some smoke but maybe not too bad. Now yesterday drained and put fresh gas in her and then things seemingly went downhill. She always idled pretty good where I've now searched 'backfiring' and 'misfiring' but always seems peoples situations are that doesn't want to idle... If anything mine idled fine, just didn't really want to go above idle. Now really won't even start and my main point is 1) perhaps at this point I have multiple problems. 2) at least one of the problems, I would call it may main issue right now, was progressive.

Where I'm at now is I think one of the backfires blew apart some of the intake pieces or maybe some were already separated a bit (possible cause for vacuum leak), I'll dive into that tonight. I noticed some gas leaking just below what I'm guessing would call the throttle body.

Now based on other threads (I did spend all night searching and reading before posting and mention this as I know there's frustration when folks post without reading and search for themselves). Sounds like most folks look toward electrical with misfiring and backfiring so pulled the distributor caps and belt was intact. It seems a little loose, I would have expected greater tension but when turned over they both spun. With even just a split second turn of the ignition to spot that, a little more fuel leaked out that same spot.

So I'm not adverse to just towing her to the shop because I want to have a reseal done anyways. However, it seems like a lot of the mis/back firing issues can be chasing a ghost and hate to think of a shop just diving in and replacing things and telling me it was still bad and end up with an insane bill and as with other's, still have issues.

So what I'm hoping for, and would great appreciate, is feedback on next steps. In particular, perhaps overall thoughts but seems like should just plan to replace caps and rotors, the points of contact in the rotors looked OK but at 90k miles, probably original and could use replacement. What else can and should I replace that's pretty easy just to get that out of the way? I read about the coils, 02 sensor and some other switches/sensors... I will check the earth/ground as I did replace the battery recently. What else did I read, hmmmm. Plug wires look good, no visual indication at all of any kind of breakdown/aging. I think a key is what would die progressively versus work/no work.

Again, at very least my objective is to knock out some of the diagnostics and replace some things, especially things that could potentially be part of the problem but also considered just maintenance, so if/when take it to the shop we can check those off the list. I do have one of the code readers bought from whomever was putting them together on the forums so I'll have to find and break that out but only got a check engine light I think once during all of this.

Haven't checked spark, haven't disconnected coils one a time, hmmm, trying to now remember common recommendations... Am I right at thinking need to check out the intake and gas issue before really thinking about much else except possibly ordering some parts...???

Thanks everyone, these forums are awesome. They scared the hell out of me when I first bought the car because you read about all these problems and a lot of time the worst of the worst but really the car has been a pleasure and been reliable and when do need something, it's awesome knowing there are such enthusiasts out there willing to spend their time and help folks out, I'm tearing up, gotta go!!! Seriously, thank you for any and all feedback!

Rocket Rob

Check for a broken distributor belt. Disconnect the secondary and see if it runs ok. Another way to check is to remove the secondary cap and see if the rotor turns by hand. It shouldn't.

PS: Welcome to Rennlist.

SuperUser

My bet is your plug-wires are shot. When mine gave out is was very quick, like one day car was fine next day it was totally not working and I had to park it.

Vandit

Gas leaking under throttle body? I don't even know how gas would get up there. Are you use it's not oil? When was the last time you changed the oil or topped off the oil?

dleefsu

Hey guys and thanks for the responses. Did check distributor belt last night, it was intact, spun with the other (turning the car over), just seemed a little loose in my opinion but have no point of reference.

Will definitely consider plug/wires. Visually wires honestly look better than I would expect for a car this age, if wiped them down would think they were new. Haven't pulled a plug...

Excuse my terminologies as I don't know the names of all the parts. It may not be the 'throttle body' but looks like where the gas line goes in and where you can rev it under the hood, where that cable connects. Tonight I'll take that area apart as a nights sleep and some more thought has me thinking again may have several problems but need to hone in on the gas issue as well. Definitely gas though unless it's engine coolant (that's a joke)! Didn't smell it but was water consistency, was a bit more concerned about an explosion but engine wasn't really that hot. One thing I was trying to do was get her up to temp to check the oil level as I'm hoping that perhaps I didn't overfill it at one point and perhaps that fouled up plugs just sitting there?!?!? My understanding is can only really check the oil hot though. Oil hasn't been changed in a while but probably just a few hundred miles on it. I was still going to change it soon as I know it's a mileage and time issue but do have to top it off often, thus needing/wanting to get it resealed as she's worse than a pet mess'n up my floors!

Andy Roe

You mention that the distributor felt a little loose. I've no idea if this is actually possible, but I wonder if the belt jumped it'd cause these issues by causing the 2nd bank of plugs to fire at the wrong time?

Vandit

You can disconnect the ignition modules one at a time to isolate the distributors. The car should run with either disconnected. They are in the left side of the engine conparment. Follow the coil wire from the distributor center. Those are the coils. The ignition modules are the two rectangular modules mounted to the coil bracket.

dleefsu

Thanks again for more responses. For the belt, I just have no reference so perhaps someone who has an idea of the tension could share their wisdom. I guess put it this way, and I will add that it looked good, not frayed, 'teeth' that I could see didn't look worn, nothing to say, 'needs to be replaced anyways'. For the tension, if it was a 'regular' belt for the usual things on a motor, I wouldn't leave it with that tension and not like it was falling off, could just easily 'flex it' with a screwdriver (no leverage applied). I guess with any belt can lose it's tension over time but seems like wouldn't cause such a quick escalation of issues.

Honestly in reading the other threads it seemed completely logical that something happened with the distributors, perhaps time to take a 'daylight' view of them (not looking forward to that back screw again) although I know I checked the belt well because in a way was a little bummed didn't look in and see it broken. Being loose and jumping a notch could definitely explain some things though but seems like also would have been a bit of a light switch going off. As soon as it happened would have known it but could still be one of the issues facing as still think have more than one issue. Will try the coil disconnect trick once stop the gas from leaking, that is if she'll run for me at all.

Is there a trick to getting the coil/plug wires off the distributor cap or just on really tight for good reason or not meant to come off? I'm generally pretty delicate so not sure if it's a time for a little muscle, or leverage.

FeralComprehension

They just sort of attach themselves over time. I like a nice round hooked probe to break the seal between the rubber skirt of the individual terminal and the cap towers. Nothing sharp as you can tear it pretty easily, just enough to lift it off where the probe goes in and then work your way around.

There are special pliers but I've never used them.

dleefsu

Semi-good update. I decided instead of taking her apart further, I probably should try putting everything back together. By everything, several of the fittings for the blower on the left that connects to various things was open. Not sure what caused it or at what point but basically found it that way (no way I directly did anything to dislodge it as I wasn't doing anything in that area at any point). It seems like there's a lot of stress point if say you loosened one hose clamp, monkeyd around and then wrestled it back into place, I found worked well to loosen all of the fittings so mostly just slid together with a tiny bit of convincing. Interesting thing was when I was putting it back together I saw and questioned what the big electrical plug was that was simply hanging down. Now good chance I could have dislodged it but it was to one of the coil modules. Really didn't think I would have done anything to dislodge it but I was working in the area... Cleaned everything up, got everything back together and fired right up and ran great for a couple minutes and then old issues returned, some misfiring... I'm calling it a night there, at least got back to the running stage, but have some ideas for tomorrow. I think may pull a plug to see how at least one or two look and then also probably order some new coils.

Thanks for all the input thus far!

onceover

If you're ordering could of suggest doing the 993 could conversion. A quick search should pull up a DIY. How old is the gas in the tank? Have you tried topping it up with fresh fuel?

dleefsu

I drained the gas the other night and I think I'm narrowing down what has occurred. First though, it is very cool these forums can be so helpful but can also be a challenge selecting the directions to head in the pursuit for finding issues. I almost made the mechanic mistake by just starting to replace things without following the leads. There's so many causes and affects and looks like I was right on it being more than one issue (wasn't really rocket science but was good knowing needed to solve one issue at a time).

Issues started with ultra bonehead, I'm too busy to think but car needs oil situation, so she got overfilled (note to newbes, pretend that inside the car gauge doesn't exist when filling with oil)! I'm admitting this with my tail between my legs so someone may read this one day and it 'fills in some gaps' in what may have happened with their car. My first leads from the forums were distributor issues, coil, plugs, wires, basically everything electrical which seems all of that is fine. I guess the clue there should have been the smoke as obviously had something more than just electrical going on, don't you love hindsight!?!?

It's pretty unbelievable though how far things can go downhill with too much oil, I still haven't determined how overfilled it was but pulled some oil out and like magic, stopped smoking. I cleaned up the entire motor but issue 2 was, and I'm not sure the cause, maybe a backfire from the oil issue blew loose the connections for the airflow on the left side of the engine which led to more issues (the progressive nature of the issues). Last night I mentioned she cranked right up, ran perfect for a minute or two (this gives me hope didn't do further damage) but that was also before draining some oil. Another issue may have been one coil module not connected and perhaps another loose. In running it though, I had another pretty bad backfire and low and behold, those fittings were loose again. Seems like it will take a little nursing to end all the sputtering and backfiring from the oil situation. I'm actually glad and already loosened all of those fittings to make sure all of them fit together perfectly. I mentioned previously there's the potential for a lot of stresses on those fittings and I found it's best to loosen all of them, get things in place, then tighten everything. The main gauge for alignment is that the one tube fits properly on the boot to the main blower. It seems that if that rests in place perfectly, all the other fittings are in the right place.

The brights side is this is really a confidence builder in working around the motor. Any newbe's newer than me, trust me when I say, don't waste time trying to work around things. Take what you need to apart, pay attention, do what you need to do, clean everything up, then put it all back together paying even greater attention. Everything needs to fit together pretty precisely, need to see what you're doing, need access... I just found myself a few times thinking I could work around things but things went significantly better once took 8 seconds and removed the obstacles. Tip #2, if you park around trees, watch the leaves inside the motor, honestly I'm shocked she didn't burn to the ground with the nice mix of leaves and engine grime which most certainly is a very bad combination!

So I'm taking a little time today to hopefully get it back together and see where things stand. I'll update once know a little more, hopefully next update is she's alive, ALIVE!!!!!!!

greg1990964

I was literally reading this and thinking it was overfilled with oil. Especially the "gas" coming out near top of the engine comment. The 91 coupe in my garage was purchased overfilled with oil and seller was told it had serious engine problems. Hope that was all your problem was. Good luck.

dleefsu

I thought the same thing as it really is amazing how badly things turned. Right now she's coughing and spitting more than I'm comfortable with (don't want to run it too much like this) so, and I hate to say this, woke up this morning thinking, if this was any other motor, weed wacker, whatever, first thing I would do if the motor was subjected to oil is check and probably change the plugs. That's my mission today, pull some plugs, may go buy a compression gauge at the same time and see what happens. I am curious if I could spray something into the heads and then possibly suck it back out as a concern is that it was overfilled, then sat a while, perhaps some varnishing if that's what it would be called. Also going to try a gas additive as well, seems like couldn't hurt.

dleefsu

Greg - How does the gas coming out correlate to overfilled oil? I think that's my last remaining mystery as a huge concern right now is if I'm dumping gas inside all that tubing, no bueno!!! Only thing I have come up with is if a cylinder or two isn't firing but not sure how it would get back up there??? It did happen at least one time after an extended crank time with no starting which I could see being a factor, maybe.