Weird running issues

[Zaffer]

I am new to these cars and still learning how the fuel injection system works. I bought the car in October of last year but didnt' attempt to turn the engine over until I replaced the timing belt in April of this year and due to a new house and toddler, don't have much time to tinker with the car. I did quite a few searches for my issue and found nothing. I am also trying to go by Artigue's troubleshooting guide, but have come up with nothing so far.

Here is what is happening: Sometimes when I start the car, the relay for the brake/seat belt lights in the dash doesn't work, and when this happens, the car will start, but won't rev, regardless of throttle position and will barely run and eventually die. When the lights do come on/relay works, the car starts and runs, though the idle is low/rough and it's hard to rev. If I open the throttle half way, it will eventually rev high enough so that when I go full throttle, it will rev all the way to red line. If I go full throttle from idle, the engine will bog down, but will eventually rev to where it will go to redline. Now, I don't have specifics on what RPM's this happens at as my tach is not working. Also, when the car is idling/revving, it sounds like it's missing, but there is spark to all plugs (plugs and wires are new) and all injectors appear to be working. I have also double checked my cam timing since I changed the belt and it seems to be good.

Here is what I have done so far with the car: 1) While the engine is running, I have gone all over the intake/fuel system with brake clean looking for leaks and have found none. 2) I have checked the function of the AFM door and it moves nice and smooth with no resistance anywhere in the travel. 3) I ohmed out the coolant temp. sensor and the numbers were pretty good with the outside temp. at around 85 degrees (I did this before running the engine). 4) Ohmed out the AFM and got the following numbers: a) Pins 6 & 8 - 362; b) Pins 7 & 8 - 320; c) Pins 8 & 9 - 201. I measured this at the DME. 5) I have new fuel in the system after draining the tank of the old fuel.

This is as far as I have been able to get. My main question is relating to the seat belt/brake warning lights/relay: Is there something else that relay connects to/powers up in the fuel/intake system that I'm not seeing on the wiring diagram, and if so, what? Is this even related or is it just a coincidence?

As for the running issue when these lights do come on, what would be a next to check? I don't think it's an issue with the cat since is doesn't matter if it's cold or warm and the car will rev to redline, once it gets past a certain point it revs real quick with no signs of a miss. I have not checked the rotor/cap or the wires to the distributor. I guess that would be the next thing? Like I said, time is very sparse with me right now, so just trying to keep on track without going down the wrong path and wasting time, though I know this will happen.

Thanks for any help and/or links that may already address my issue that I haven't been able to find.

[2500diesel]

Check your spark advance.

[Kevin1]

Tach not working could indicate a bad magnetic pickup in the distributor, which could also account for the running problems. First, though, make sure all grounds are good. Ground pods under dash, on the inside of the fenders under the hood, FI grounds on the upper intake nanifold, and at the left tail light inside trunk.

[Zaffer]

The ground pods had been a consideration, just didn't know where they were. I'll probably check them this weekend and/or remove them for clean up. I was wondering about the tach and how it worked with the distributor. I'll have to take a closer look at that as well. Are parts available from I.A. or Vick?

[2500diesel]

Pop the distributor cap and do a visual inspection. In particular, look at the thin wires to the pickup. And yes, check the grounds.

[So Cal Mark]

since you replaced the timing belt, have you verified the alignment? It sounds like the belt is off by a tooth

[bradartigue]

You have at least two problems:

One is electrical - there is no relationship between the instrumentation lamps and the fuel injection system except that they are both tied to the battery via the ignition switch. I would inspect the ignition switch wiring as it the point tying this stuff together and, as noted previously, check the grounds.

One is mechanical - as noted you need to recheck your timing belt. With the crankshaft aligned to 0 degrees BTDC are both camshaft wheels aligned to the pointers on the cylinder head? If these are correct then is the rotor on the distributor pointed to the #4 position.

[Zaffer]

I haven't re-checked the timing since I've run the engine. When I replaced the timing belt, I turned the engine over three or four times (according to the cams, so 6-8 times of the crank) and the holes in the cam sprockets lined up with the pointers, but I need to re-check since it's been running, hopefully sometime this weekend.

As for the distributor, I haven't checked anything in there yet. So, when the engine is at TDC, the rotor should be pointing at cyl. 4? Weird. I'll check that as well. I still need to replace the rotor, cap, and fuel filter as well.

Thanks for all of the advice thus far and it's great to be involved in a such a great community!

[wetminkey]

It's pretty bizarre, so here it is straight from the shop manual:



Hope this helps,
Todd.

[Zaffer]

Went out this weekend and adjusted the distributor by ear and it helped some, but the erratic miss is still there. Looked at the wires to the magnetic lead and they are pretty goobered up (jacket is cracked/missing in places). Will be ordering a new magnetic pick-up, rotor, cap, and fuel filter next week and see if this helps.

I also put a can of BG 44K in the tank so hopefully this will help clean out the fuel system as well and clean it of possible varnish in the system. I'm hoping to get the car on the road by this fall so I can enjoy it a little before winter hits!

One other thing, could there possibly be an issue with the ignition module, and how would one go about checking that?

[bradartigue]

One other thing, could there possibly be an issue with the ignition module, and how would one go about checking that?

With a multimeter. Check your shop manual for the procedure. Easy to do. If the thing is running at all then it is unlikely the module is fried; frayed wires in the pickup definitely can cause problems though. Replace only the stuff you know is bad right now, otherwise you'll just create more problems. Replace the pickup and drive it.

[Zaffer]

Thanks for the info. I figured either the module works or doesn't, but just wanted to be sure.

I knew I was going to have to do some things to the car as it only cost me $700, however the floors are solid as are the fenders and shock towers. The only real rust on the car are the rockers, and even they aren't real bad. The paint is original, but the interior is in pieces as the PO's son was trying to put a sound system in the car . They threw the passenger seat out as the frame was bent and they were planning on replacing the seats with ones out of a Neon, so trying to track down a seat for the car. The driver's seat is in pretty good shape as is the rear seat, and the other interior pieces are there, just need to sort through them and see what needs replacing.

[Zaffer]

SO, I still haven't had time to get the magnetic pick-up, hopefully next week.

Anyway, I removed the cap to my AFM and everything is in pretty good shape. On that note, I have a question concerning the fuel pump contact. The metal rod was just out of adjustment so that when the car was on, the pump was all at all times. I adjusted the rod, but what is the gap supposed to be on the contact. I would hate to put it all back together only to find out I have it too far out for the pump to turn on when there is air movement at start-up.

[Zaffer]

UPDATE: I FINALLY replaced the magnetic pick-up in the distributor and no change in how it runs; also, my tach still is not working, though that is down on the list at the moment.

Anyway, I'm still having issues with it running/idling well at low RPM's and revving in the lower range; the upper range seems okay.

Here is what I have done so far:

I timed the engine with a timing light and this timing light is digital so you can set the timing on the light and it also tells you the RPM's and I set the timing on the #4 wire.

While doing so, I noticed the mark on the crank pulley was WAYYY off, as in 15 degrees BTDC. I set it to 10 BTDC and the RPM's dropped to around 700-750 (fluctuating), though throttle response was a little better. I attempted to time it to 0 (TDC) per the manual, and I got it there, but the car kept threatening to die and the idle dropped to approx. 550 or so.

Just for giggles, I decided to see how much the idle would go up as I went more BTDC and at around 26 degrees BTDC, the RPM's were around 1000 before they started dropping off again. I re-checked my timing using the little windows on the back of the timing cover and the exhaust is bang on, but it's hard to tell if the intake is on or not. How many degrees is 1 tooth on the cam gear, and if one swaps the intake and exhaust cam gears while doing a t-belt and replacing the cam seals, what would happen? I turned the engine (cams) two times and then two times again before putting everything back together and everything seemed to line up pretty well. Also, the rotor, more specifically the dot on the rotor lines up with the mark on the distributor body when the crank is at TDC.

Based on what is happening, though, it seems that my timing is off, but nothing is jumping out at me at the moment. I REALLY don't want to have to remove the coolant tee and the timing cover just to check everything, but that seems to be the only thing left, as far as I can tell. Any other ideas? Also, how does one tell the exhaust cam gear from the intake cam gear? How does the DME fire the injectors (crank sensor, cam sensor, etc.)? Is my thinking along these lines accurate, and does anyone have a good explanation as to how the car idled faster that far BTDC? Even though idle was faster, throttle response was worse.

Thanks for any input/advice!

[wizard124]

Dash lite issue:
The "Exhaust Sensor" lite should come on with the key then go out on its own. Make sure the bulbs are not switched. The BRAKE lite should be on when the parking brake is set or low fluid.

AFM:
The resistances you read should be good to go. I had a loose pin connector in the plug at the AFM. In my case it caused a rich, sooty idle and the car barely ran. Pull that plug and see if a connector has slipped back. Spray some electronics cleaner while you have it apart.

Cam wheel timing:
If you are within a tooth either way, the engine should still rev. I went through a rough running condition after I replaced the belt. I adjusted the cams a tooth in each direction trying to get as close to the marks as possible. Still ran bad....it was my AFM. I changed out injectors, ignition module, etc. The AFM was my last final hope.

Have you pulled the plugs and done a compression check? Since the condition of the engine is unknown to you, you might have a burned or bent valve, lack of compression in a cylinder or 2 causing your rough idle condition.

Major vacuum leak from the brake booster or through the Aux Air Valve? Pinch off those lines and see.