I've been stranded by my SC!

[Ryan A Harris]

This hasn't happened to me in years, being stranded by a SC. Really hasn't happened to my much at all, but it happened today.

Here's the whats-what. Fraser's old car has been running good, not great but good. I'm getting poor gas millage, but that is most likely because I asked Fraser to "de-tune" it for 89 octane. After drives when the car gets warmed up, I get the ever frustrating "hot start" issue. Which I still haven't got nailed down yet. That's not today's problem(at least I don't think it is).

After starting the car, and clearing off all of the snow I start my drive to work. The car needed one blip of the throttle while clearing the snow off. That has been normal for this car, it won't stall out, just the idle drops very low, and the car fights to stay running. One blip and all is good after that. So I do the short drive to reach the on ramp, get onto the highway, no issues. After maybe 1-2 minutes of 100 km's(1800 RPM, 5th gear) driving the car starts to BUCK, I quickly push in the clutch, the bucking is not in the drive lina, as I can not feel it after clutch is depressed. I look at all gauges, no CEL or upshift light. Aftermarket oil pressure is still reading 58-60. Wideband is reading between 18-20(that's what is stays at while cruising), tach is working, but I can see it jumping up & down in a range of about 400 RPM. No smells of coolant threw the vents, or burning oil anywhere.

I pull off the highway, and limp back home, with the car bucking with any type of throttle, I never even tried WOT for the bucking reasons. Got back home, pulled into he driveway, guess what, bucking was gone.

I 1st thought I broke the balancer, until the bucking went away when I got home. It could be on it's way out, or the bolt has broken off. Yesterday I filled the car with gas, it was VERY empty, and I had it sit all weekend with no gas in the tank. It could be the fuel pump(as I don't the age of it, or what one is there,stock or bigger). I know I could have picked up some crap with the low gas level.

Without the CEL, or upshift light coming on, I'm sort of lost as to what this could be. Taking the morning off to see if I can find the trouble.

Any input would be great guys, thanks.

[HoseHead]

Bottom feeder gas? How's it run with fresh fuel cursing through it's veins?

I had a '90 that gave the same symptoms, but the car would eventually stop running, and usually when I was on a 400 series highway boxed in by dividers....scary place to be.

It ended up being the heat sink compound under the DIS module. Over time it leaks out and then the module overheats and shuts itself off. Once the engine cooled down (and an SC engine takes eons to do that) all was good. It took forever to trace it, but I picked up some heat sink compound from Radio Scrap, layed it on the DIS mounting surfaces and never had that issue with that car again.

Bruce

[Miller]

I had the same kinda crap happen to me befor. It would buck really bad but I had no CEL. it would be fine then start bucking reallllllllllllllly bad nomatter what throttle, sometimes even just rolling down the highway with foot off the gas. It ended up being one of the wires were a littttttttttttttle loose on my DIS.

[Mike8675309]

Seems like an overly lean condition. I know you say 18-20 is what your AFR normally shows, but I can tell you that is too lean. That said, maybe you have an exhaust leak causing that not to read correct.

Some things I've seen cause that.
#1 - worn through wires on the o2 sensor leads grounding out on the chassis while driving.
#2 - Something in the fuel tank or fuel filter restricting flow.

Both of the above result in an overly lean condition which creates extremely inefficient and hot combustion resulting in a car that is bucking.

[1HUMINBIRD]

I would start with the fuel filter. Had a similar situation with my F150. Fuel filter fixed it. Check items that others have mentioned, of course, but it sounds like a fuel starvation problem. With running low on gas, you may have clogged the fuel filter and now its junk.

Hope you get it fixed.

[90coug]

Originally Posted by Ryan A Harris

tach is working, but I can see it jumping up & down in a range of about 400 RPM.

I would start with cleaning and applying fresh heat sink compound to the bottom of the DIS. I would also look at the CAM sensor and the wiring going to it. I once had a similar issue; it was either the DIS or a crimped wire I found going to the CAM sensor.

GL

-B

[S_Mazza]

I think it sounds like the DIS module is a very likely culprit. The on-off nature of it sounds very electrical to me.

I have had DIS modules go bad on 3 separate occasions. Both times, the car ran like garbage, then perfectly, then garbage.

[Ryan A Harris]

I just finished up putting some heat sink on the DIS, and putting in a new fuel filter. The filter was definitely old, and could have been 1 of the reasons for the bucking this morning. I spend some time driving around after those 2 things were done. Once I got back into the driveway I shut the car off, it started right back up 3 separate times.

Only once today did I get the bucking, or surging I guess I would call when not moving. This was the 1st time I started it up after the heat sink was put on the DIS. I shut it off, and started it up again, it was gone. I'll have to monitor this to see if the trouble happens with the same symptoms.

Mike, at WOT the readings are more like 12-13 on the gauge. As I had mentioned, I think the reason for that is I asked Fraser to de-tune the car before I picked it up off of him. If I remember correctly he retarded timing by 4 degrees across the board to be safe for 89 octane. I now want to get the car tuned properly for 91 octane, and not worry about trying to save a few bucks at the pump for more money being spend down the road on repairs.

Now that I have swapped in a few parts, and had some trouble shooting time on this car, it feels more like mine.

[seawalkersee]

So, it was missing while you were coasting? Anytime the tach starts to act up, you should look at either the DIS or the CAM sensor. Pop the top on it and see that the magnet is still in place. Does the car start the first time, or do you have to crank it seperate times? The DIS sensor went out on mine and it was on a sunday. Picked one up at orilleys since the dealerships were all closed. Car idled better and drove for about 10ish miles. Then, it started the bucking and such. It got worse as the day went on and by monday, it was all I could do to limp it up to the speed limit and coast as far as I could and then speed back up. Swapped back to the Ford unit (at least it was consistent at higher RPMS) and took the new one back. Got a Ford one and have not had a problem since.

SWS

[Shoe]

sounds like to me Ryan your going in the right route now,by tuning back for 91 octane,our cars allways run good on 91 or better

[ALS35]

Ryan;
I experienced this very same problem with my anni once. It was intermittent and the only way to duplicate the problem was to short out the CAM sensor. Changed the CAM sensor and never saw the problem again. It was an unholy bucking that felt like the engine was firing out of order.
Alan

[seawalkersee]

The thing that leads me to believe it is the cam sensor is that it does not happen all of the time. If it is going off of the sensor, it starts to backfire and buck. But when it does not see a signal, it uses a stradegy of 33% which it will fire the plugs at 1/3 of the rotation. When it does that, it does not use the input from the CAM sensor, it uses the crank. If it was/is the DIS, MOST OF THE TIME, it is all the time.

SWS

[Ryan A Harris]

Does anyone have a known working CAM sensor? If so could I swap- in that for a few days? I have not had to bucking issue again, but I just had to hot start issue again today. At least this was in my driveway after getting back home.

Today I had found that a couple of couplers for the IC had worked losse, so I had a couple small VAC leaks. Which have been adding to my problems. Also looks like when I'm into boost I am getting some oil to leak out of my SC top to IC coupler. After my drive today I saw some oil spray on the valve cover. I'll have to get that fixed ASAP. The car is idling great, pulling around 19-20. So thats why I think that oil is coming out during boost.

Mike, My wide band gauge has lately been only flashing at 7.4. Seems like its not working at now. Has done that since about Thursday now. Just before that I was getting better readings, around 13-15 during cruising. I will have to see if I can find some answers on that from Innovative products. I'm sure they will have some info for me.

[Mike8675309]

When i replaced the cam sensor on my car, and I had confirmed it was bad, I took a hard look at it, and it appeared that the cause of issues was related to corrosion. The sensor element itself had some corrosion on it's surface and it appeared that the plastic around the sensor element had expanded slightly due to the corrosion. This indicated to me that perhaps some moisture had taken hold inside the senor body causing corrosion on the ferrous metal lead to failure.

So you might inspect the sensor to look for corrosion as an indicator of an issue.

Every issue I have seen with wide band sensors has been related to one of three things. #1 - the wide band sensor itself is failing. #2 - bad or incorrect grounding. #3 - poor quality connections. Innovate devices are particularly picky about reference grounds for their systems.

All that said.. checked your battery cables or charging system? Low voltage or corroded battery cables can lead to all sorts of weird results.

[rzimmerl]

Do a free air calibration on the wideband sensor, it may resolve that issue.