Black Smoke, Surging, and Bucking at idle and low Accel

[starman89]

Hey all, I have an 89 Conquest that I've owned for about 18 months now. I love this car but I must say it's one of the hardest cars I've ever had as far as maintenance and troubleshooting goes. In the last 6 months I've replaced the 02 sensor, the spark plugs and wires, the secondary injector, alternator belt, removed BOV, oil change and filter, and replaced all vacuum lines. I can't figure out what is causing the problem but it all started when I noticed my 02 sensor wire had broken off. I promptly replaced the sensor and this did not resolve the issue.

 

This is how the car acts:

 

 

During Idle:

1. 
    
   
2. Black smoke comes out of the exaust.
   
3. The car also surges randomly.
   
4. The surging can dip low enough to cause the car to stall.
   
5. Car can stall when coasting at any MPH in neutral, but it most commonly stalls when coming to a stop in neutral or a few seconds after coming to a complete stop. Car only stalls when RPMs are at idle.
    
   

During gradual, slow acceleration (Primary Injector?):

1. 
    
   
2. The surging continues in a different form when accelerating slowly; the surging becomes violent bucking of the car.
    
   

 

When Accelerating quickly, or launching the car (Secondary Inj?):

1. 
    
   
2. When accelerating quickly from a stand still, or launching, the car will studder instead of bucking and move much slower during the studder until you let off the gas for a second and then proceed to accel again. Then if you accelerate quickly once its rolling the car will drive smooth and seem fine, just not as fast as it should be.
   
3. Accelerating quickly from a roll, in other words just speeding up, the car will drive very smooth, no bucking or hesitation, but the car still should be faster. The car drives it's best between -5 vacuum and 10psi.
   
4. When speeding up or launching, regardless of if from a stop or a roll, the boost gauge continues to spike higher and higher and as this happens the car does not react to the boost by accel'ing and you must cease the accel or studdering can occur or even worse the boost will continue to rise way too high which is just dangerous. (I realize some of you may say this happens because of the BOV being removed but it never did this in the past when I took off the BOV, and also I thought the wastegate had a method of controlling max boost as well...)
   

 

 

Also, the black smoke goes away after about 10-15 mins of running the car, a little bit after temp reaches optimal. Another strange symptom it has is the force at which the air vents blow out air is a lot weaker than it usually is and this changes from time to time slightly, I don't know if that is relevant but it seems related.

 

Anyway, if anyone can give me any hints as to what this could be or how to fix this issue, I would be more than happy to try your ideas. Right now my guess is that it's the pigtail connectors for the injectors, the primary injector itself, the fuel pump, or the installation of the o2 sensor or the unit itself with a problem(I bought sensor brand new without a wire and soldered the wire on). I just dont want to blindly buy parts hoping this will fix it without a little reassurance and understanding. Thanks in advance guys you always have great insight... I am your student, lol.

Edited September 20, 2009 by starman89

[Strikeking10]

If someone does know what causes this plz let us know since my car has many of the same problems and i would like to also find out why.

[jettajody]

Okay fellas!!! My car isn't perfect but close and have had similar issues as everyone else has to I'm sure.. First try to score a boost leak checker and run a course. If you are leaking all around the TBI, then you need a rebuild kit. If your injector clips are original than replace with new ones. Sometimes you can file down the contacts and get some decent results. Check the hose on wastegate to OVCP and make sure it isn't damaged. If it is in good shape than diaphram in wastegate acuator is old and done. Have you checked your vac. advance, suck on it and see if it holds vac. If not than its bad. Test your OHM's on the injectors should be at 3ohms on each, IIRC. Do a TPS/ISC reset and after base idle and all vac/boost leaks are fixed then set your timing to 10 BTC. Check fuel presure with gauge, and if you are still having probs then check the codes.......... Just my 2 cents hope it hepls as it has brought my quest back to life..

 

BTW - pull and check EGR to make sure its corrosion free, a bad or clogged EGR can cause great probs..

[Edde]

Running very rich like this will be serious trouble in no time at all. Do an oil change immediately and don't drive it with black smoke. Excess fuel in your mixture WILL wash down your cylinders in gas and ruin a set of rings.

 

This is usually caused by one of a few things: Bad injector shooting fuel instead of spraying, bad coolant temp sensor for the ecu, or boost plumbing leaks - or all three.

 

The fuel system is intimidating if you haven't much experience with it but it is really VERY simple. Get a service manual from starquest garage and go thru fuel system troubleshoot/testing in the book order. You can inspect injector spray pattern and look for leaks by pulling the OVCP pipe and running the pump off the test wire. I guess you'll need to check pattern by cranking the engine with pipe off (and coil wire off) using a helper but you can energize the pump and look for drippage on your own.

 

It's hard to say about inside air but the foot/face actuator in the cabin does work off of vac from the TB. If a check valve is missing or damaged it can allow boost into it.

 

But generally speaking a volume of black smoke is not caused by a smallish vac leak.

[Indiana]

Your accordian hose have any tears or leaks? It can't. The primary injector is dirty and was that secondary "new" or just different? What do the plugs look like? Unplug that secondary injector and start the car and it should rev up just fine up high rpms as long as you do that slowly. If it can't rev up that primary injector is likely the problem if the plugs are clean. The secondary is only going to come in with the car not moving under load if you move the throttle quickly and its the quick tps movement that tells the ecu to fire that injector. You have a bov? Remove it it may be leaking at idle or while driving and see if that helps. Nasty crusty fouled plugs can't clean their self up. You have checked wires under there and the CTS plug isn't on the temp sensor or something like that? The CTS plug has a molded rubber end and goes on the oval end two prong sensor, that rubber boot may be broken off but the molded ends around the wires should still be there.

[austin88starionturbo]

Just a thought unplug the mas and see how it runs my car is doing the exact same thing runs fine with out it let me know what happens I'm haveing probs with it

[starman89]

The car has fresh oil, new spark plugs, and new spark wires. I am aware that it's running rich cause it fouled a set of new plugs in no time. So I have taken proper precautions already as well as not driving it as much. Before this all happened it was my daily driver but now it sits in the garage and I run the car for 5 mins or so about twice a week to keep the car alive.

 

What confuses me is why or how the problem could be more than one thing. I realize it's an old car but all the symptoms arouse at the same time. I think it may be because before I figured out my 02 sensor was broken I ran the car for about a week. Maybe that could have damaged other parts, running the car with a broken 02.

 

Also, I already have the manual, it's an awesome book (I even have the electrical manual) but I still periodically need help from you guys online because the book doesn't always have a clear answer. For example, I can't find the vacuum advance anywhere in the book. Does it look anything like the EGR valve or the FPR? Or does it perhaps have another name in the manual? Should I check the EGR as well anyway as jettajody suggested?

 

 

To Edde, I forgot to mention, the Coolant Temp Sensor was replaced by a mechanic already and it helped the surging a lot but not the other issues. So good call, that was part of it but it did not solve the acceleration, black smoke, stalling, etc... so I'll check the inj. and think about buying a hand vacuum to test for boost leaks.

 

To austin88starionturbo, The car runs like crap with MAS unplugged but I've heard of older pre-87 starions runnign good w/o mas. Didn't help me tho.

 

To Indiana, I removed BOV a while ago and it made no noticeable difference =/

 

 

As far as the Injectors, The 2nd inj replacement works great. It's a used one I bought from someone on the forums. The primary inj definitely could be a problem, In fact, the Primary Injector was one of my first guesses as to what the problem could be. I wonder if the fact that I didn't replace both injectors at the same time had any effect on the Prim Inj? Or running the car without an 02? So I will test it by taking off the OVCP and running the car, then looking with a flashlight down the tube to see if the inj leaks or sprays right.

 

Thanks for the input on this once again, I think this post will help a lot of new starquest owners and hopefully if I can fix the problem ultimately, I can help other owners with this common problem.

[Edde]

Running w/o an 02 is not gonna cause this. The vac advance unit is a gold saucer attached to the distributor and has one vac line to it. If you pull any vac on this is must hold forever basically. If it pulls air straight thru then it's a gonner. It also doesn't generally cause this. It most frequently just causes a buck or cough at about 3k under load. It should not be seeing vac at idle so technically it couldn't be a vac leak (at idle).

 

EGR unit and passages in the intake get clogged with carbon so yes at some point, but no it won't cause running super rich.

 

Swapping injectors one at a time is no big deal either.

 

Either a screwed up injector or a major plumbing leak... and I always say or both just to cover my a$s

 

Black smoke at idle really seems like injector or CTS. Boost plumbing leak wouldn't show up at idle unless a hose was dangling loose. Then it would barely run at all.

 

I suppose you are positive the injector clips aren't reversed and that they are both in good shape.

[starman89]

I suppose you are positive the injector clips aren't reversed and that they are both in good shape.

 

No they are in bad shape and they twist, they get messy and taped as they descend from the TBI, which means I don't think theyre reversed but Maybe just bad. I've tried to clean the contacts but it didn't seem to help.

 

Where can I find a good pair of pigtails/clips?

Edited September 26, 2009 by starman89

[Edde]

Bosch makes a connector we can use. I'm not sure who sells it - but they're pretty widely available. They have long leads on them so you can go back a ways in the old wire and find some metal that's clean, not green or brown. Solder and shrink tube them as opposed to using wire caps.

 

 

[austin88starionturbo]

Ok thanks that's odd my 88 runs great with it unplugedhm mmmm dam ok bad MAE prob eAny one el e have this problem