Car runs and drives again but......

Good afternoon

Take a look a the DIS harness connectors. Check for exposed/damaged wiring. Swap it out if you have a spare. I have posted my experiences with a defective harness which had similar malfunctions (erratic/lost tac, bouncing/bucking and or engine shut down).


Good luck.
 
decipha said:
does PP mean professional products?

if so thats most likely your problem

how did you set it correctly if you couldn't reach base idle ??
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Since the removal of the chip there has been no idle issues. It does hang and take some time to come down to proper idle but it does come down and idles perfectly in the 600-750 range on the stock tach. Scratch that whole PP TB being the problem.

Sam you make a great point. That harness would have been removed when the engine came out so it could be loose somewhere. After all I couldn't remember I purposely left the jack shaft pulley bolts loose until I had the belt on to make it easier to hold and tighten until after I had started the car and wondered why there was a wobble!
 
That said I took the car to run errands again today. Once again about 50 miles round trip. About 3-4 miles from the house it once again decided to do the bucking thing running down the hwy at 2000-2100rpm or about 60mph. It did not clear up right away and was slowing down even as I would give it more throttle and boost would come on. I quickly pulled over, noticed even the idle was bouncing around and very low, 500ish rpm and shut the car off. I immediately restarted the car and had no more trouble for the rest of my trip. Is this pointing to the ignition switch? Once again upon start up I had no tach signal and then a few miles down the road it was suddenly back.


This is the exact symptoms I described earlier/above, mine appeared to be a bad signal from the cam sensor. When it happened it bucked as you describe, on restart usually had no tach, may take several tries to start as the PCM "guesses" when to fire injectors. The car then ran fine, sometimes the tach sig would come back, sometimes not. My conclusion was NO cam sensor signal was better than a BAD signal. New cam sensor, and it has not happened since. Easy to change.

Adam
 
Good to hear Adam. This is an engine that has been sitting for several years. I just dropped it in and hoped for the best. Being the old engine has a new cam sensor on it this is an easy thing to try. Will be kicking myself for not doing it when I swapped the balancer though...... Still doesn't explain why it happens less frequently with the chip removed though.
 
Feeling comfortable with the way the car was running I decided to put the chip back on the car today. I wrote a new base tune from a stock bin. I changed only Egr setting, injector size, and MAF transfer. On the test drive it was bucking again more frequantly than when the chip was off. I however did not have to restart the car for it to clear up. I was able to get a short datalog before the lap top battery died. Looking at it it appears to be a timing issue. At closed throttle and say 50mph it is only commanding 20-25* of timing. Under these low load conditions it should command more timing for emissions and fuel mileage concerns. Looking further at the datalog it appears from when I remember the bucking happening and and correlate It to the datalog that it is also pulling timing. Could this be a bad knock sensor?

I double checked the DIS harness and it is connected tight and without any frayed wires. It did start hard yesterday without the chip installed, kind of like hydro locking. The last engine had this same issue so as much as I would like to point my finger at the crank sensor I find it unlikely as it is two different sensors causing the same problem. This does not me it is not or I won't change it, as I have several here. It does seem like it could be at least part of the problem. Again what about the knock sensor?

The high idle is also back with the chip also, 1300rpm or so with no signs of coming down.
 
jdsgallops said:
Feeling comfortable with the way the car was running I decided to put the chip back on the car today. I wrote a new base tune from a stock bin. I changed only Egr setting, injector size, and MAF transfer. On the test drive it was bucking again more frequantly than when the chip was off. I however did not have to restart the car for it to clear up. I was able to get a short datalog before the lap top battery died. Looking at it it appears to be a timing issue. At closed throttle and say 50mph it is only commanding 20-25* of timing. Under these low load conditions it should command more timing for emissions and fuel mileage concerns. Looking further at the datalog it appears from when I remember the bucking happening and and correlate It to the datalog that it is also pulling timing. Could this be a bad knock sensor?

I double checked the DIS harness and it is connected tight and without any frayed wires. It did start hard yesterday without the chip installed, kind of like hydro locking. The last engine had this same issue so as much as I would like to point my finger at the crank sensor I find it unlikely as it is two different sensors causing the same problem. This does not me it is not or I won't change it, as I have several here. It does seem like it could be at least part of the problem. Again what about the knock sensor?

The high idle is also back with the chip also, 1300rpm or so with no signs of coming down.
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Low timing advance at cruise should not cause bucking.

The car idles high only with the chip installed? What is the timing like at idle?

Have you looked at the cam sensor? The car can run without it, but may take multiple tries to start. You can try unplugging it, start it up, and run without it for a while to rule it out.

Any chance that the harmonic damper outer ring has separated from the rubber holding it to the inner hub?
 
Balancer looks good. I replaced the one that was on the motor with the one I pulled out. Looked much better very little cracking of the rubber.

I took it on another good drive last night, about 50 miles round trip. Was able to data log there and back. MAF is nearly dead on. Car ran the same with the chip as without on this trip. The idle is still high with the chip approx 1000rpm.

Watching the dashboard as much as I could while driving the engine does not seem to be the bucking issue as the rpm did not changing during any bucking situation I was able to see live. Between this and having the same symptoms with both engines I am thinking ignition switch again though would not rule out the cam or crank sensor. I think ignition switch is the place to start though as the car is 25 years old, appears to have the original switch still in it, and has 200 or so k on it.
 
aroot1 said:
I've got a '90 XR7 that gave me intermittent driveability issues (sometimes days between, some times a week or more, others EVERY time I started the car). It was bucking while driving under any conditions, as if losing all power, then coming back on again at a rate of about once a second. Would often clean up and drive fine if I shut it off and restarted, BUT on restart I would have no tach. It would also sometimes give a hard start as you describe and "kick back" as I let off the key. I swapped out cam sensors and it all cleaned up. I'm not sure what your drivability behavior is, but some of the other symptoms are similar

Adam
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We appear to have a winner here. It starting bucking as soon as I got on the interstate Thursday night and wouldn't clear up. So I pulled over to restart the car. Did not want to restart. After many attempts it finally did and no more issues on the way home. So I installed the cam sensor from the old engine. Fired right up and seems to be running smoother. Has not bucked in 2 days now, though I have not exactly done my normal driving routine. The old sensor did seem to have some copper dust in it so I am hoping this has resolved the issue. Thanks for the help!
 
Cool.

Interesting that you had that "dust" on it. I also saw a grainy dust like stuff stuck on mine. I figured it might be rust, and the switch being magnetic it could have been the whole problem. Never bothered to try to clean it up and put it back in, if it ain't broke , don't fix it, or, if it's fixed leave it the hell alone!

Glad that seems to have been what you needed, and a bunch easier than some of the other paths it might have gone!

Adam
 
No bucking since cam sensor install. Seems to have done the trick. My dust was thrown out on each side of the pickup. I didn't figure it was worth trying to clean. I figured if there was dust it was a clearance issue and cleaning wouldn't make a difference. Though I am curious how the dust would form?

Did have one "hydraulic lock" type start with it since the sensor install. Going to chalk that up to the ignition switch as the blinkers are still an on off thing, along with many other electrical accessories. Some times it is baby steps. One minor issue down countless more to go. The car is such a joy to drive though. I enjoy it more than the 11 and it is my daughters preference also!
 
Copper colored dust could be finely ground "Oilite" bushing material from down inside the cam synchro assembly (below the cam sensor head). Or it could be rust, possibly.
 
Well it's back but in a different way.

I took the car to work one day, about a 30 mile drive, and about 1/2 way there going down the interstate the car started to buck. It would not clear up. I pulled over inspected the car and could find nothing wrong. The car restarted hard and ran poorly. A mile or two down the road it cleared up and ran normally the rest of the way to work. Turning the car off and restarting after work had it running poorly still. I leave for the night and start the car and it is running normally. Again a little before 1/2 way home it lost power, bucked, and ran poorly. This time it was noticeable, easier in the dark, that the car would run normal with check engine light off, poorly with it on. It would go off and on for a few miles before it finally stayed on. Car was well down on power, at 0 or positive boost the rest of the ride home. By the time I pulled in the driveway the car would barely idle and it was idling about 400 rpm and going down.

A quick search here pointed the finger at either the ignition switch or the DIS. Being I had an ignition switch here I elected to replace it before going any further. I just finished replacing the switch. Even after the battery being disconnected for over a week once the car was started it was still running very rough and the CE light was still on. The car does not want to rev and idles very low and wandering. The car is starting very hard needing several attempts to start.

Is there a way to check the DIS? There is no up shift light on crank.

Reminder this engine was pulled out of a car that had sat for many years. I only switched over what I needed to to drop it in. If the DIS is not the issue could it be the knock sensor from sitting so long, thus pulling timing there the loss of power and rough running?
 
Sounds like it's defaulting to basic lookup values (limp mode). Might be a failing/failed ECU.

Any codes?
 
I have not pulled codes yet. I have yet to figure out how to do it with EA. That being said I intended on taking the car for a drive to get a datalog to see what was going on but the car was running so poorly that I put it striaght in the garage before it quit running. It did not seem to log even for that short time or show anything on the dashboard.
 
Still at square one.

Did some digging on the forums today to help solve this problem. Although it sounds like a DIS issue I am tired of throwing money at the car and want to be sure what the problem is before I buy anything else.

Random post had someone with a melted plug wire with same symptoms. Checked plug wires all are good.

Finally replaced the ignition switch. No noticeable change with it. The old one was starting to separate so it was going to be needed sooner or later. I still have what seems to be a big draw when trying to start the car making it almost kick back or die when trying to start. Only happens if cranked for 30ish seconds or so.

Tried pulling codes today. As I was looking up how to jumper the wires I remembered I had a code reader here. Plugged it in and let it do it's thing. After 10 minutes it was still not flashing any codes nor was the CE light flashing. Was going through the self check as you could hear all the solienoids clicking. It seemed though that it checked everything multiple times and never went into flashing the codes. After the 10 minutes I pulled the reader off and the fan continued to run along with all dash lights remaining lit.

This car has me at wits end. I am to the point I am concerned it has electrical gremlins that can't be found and it may be time to part it out.

Tell me what I am doing wrong here what the problem could be before that happens!
 
Tried pulling codes today. As I was looking up how to jumper the wires I remembered I had a code reader here. Plugged it in and let it do it's thing. After 10 minutes it was still not flashing any codes nor was the CE light flashing. Was going through the self check as you could hear all the solienoids clicking. It seemed though that it checked everything multiple times and never went into flashing the codes. After the 10 minutes I pulled the reader off and the fan continued to run along with all dash lights remaining lit.
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Sorry if this has already been suggested, but that sounds like a bad ECU to me...
 
Yes you have mentioned that already. Should I still not be able to pull codes? The only other time I had a computer go bad the car would turn over but not start. We eventually found a bad ground in the computer. In this case the car will eventually start and run, though very poorly. I drove it this way for nearly 60 miles going to work and back. What about the symptoms I have reported makes it sound like a bad computer and not the DIS?
 
jdsgallops said:
What about the symptoms I have reported makes it sound like a bad computer and not the DIS?
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My opinion is that an issue with the DIS wouldn't cause the issues you just described when trying to pull codes. How many times now have you successfully pulled codes on that car so far?
 
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