Hello!
Similar to Ropadopa, I recently acquired a 1996 X90 – I got mine from a co-worker, and it has what appears to be a pretty good misfire when the throttle is applied quickly. He had been troubleshooting it for some time, and finally gave up after he could not resolve the issue. I had been looking for a G16B to put in my Samurai, so he sold me the X90 for next to nothing to get it out of his garage. The car drove fine for approx. a year after he got it, but about six(?) months ago it started acting up with the misfire condition. Just short of 90K on the odometer. Rebuilt/salvage title.
Feathering the gas pedal will allow it to rev to redline with no issues, but anything more than a moderate press on the pedal results in the misfiring condition. It will eventually stumble up to about 3000 RPM and then rev up normally. If the pedal is fully floored at idle, it will pretty much chug and burp until the pedal is lifted. The exhaust smells like it is running rich when misfiring, but it is not putting out black smoke. The fast idle at cold start works normally, but at idle when warm, there is a slight intermittent misfire.
Reviewing the forum posts for similar conditions here, and consulting a borrowed FSM from the previous owner (PO), this is what I have checked so far:
Compression check (warm eng, WOT): #1 – 185#; #2 – 195#; #3 – 187#; #4 – 186#
Engine vacuum is 21” Hg and steady;
Installed Bosch cap, rotor and wires;
Ignition timing with freeze jumper is 6 deg., crank pulley bolt is tight, but I did not verify cam timing marks;
No cracked exhaust manifold tubes;
PO installed new cat;
FPR testing: Key on – 39#; Idle – 33#; Key off – 31.5# and will hold it for well over one minute. Applying 26” Hg to FPR nipple shows 31# (should be 21#?) Have not done shunt test (pinched vacuum line to FPR).
EGR valve responds (tries to stall engine) when diaphragm is pushed, FSM live EGR test shows normal ops;
Removed and cleaned dirty throttle body, which helped, albeit minimally.
The PO had a low dollar code reader and said that the car had generated a P0300 awhile back. I bought a Autel Autolink AL619 scanner as it will read some live data. It showed no DTC’s stored, or pending. It shows that the TPS appears to be working normally with key on, engine off. Using the live data feature, I generated this readout using all PID’s available (see attached file).
The data can be downloaded and printed out as a text file and it is output in ‘frames’, which are cumbersome to compare – for me - with all the pages generated. I entered all of the data into the attached MS Excel file for easier review. RPM is highlighted in a red font, and I highlighted “Frame 15 & 16” where the induced misfire condition was taking place.
What the data shows is 15 seconds at idle, 15 seconds at 1500 RPM (trying my best), 15 seconds at 2500 RPM, 15 seconds at 4000 RPM, then 15 seconds to stabilize at idle. Then 10 seconds with the gas pedal floored, causing the misfire (frames 15 & 16), then a final 15 seconds to stabilize at idle again.
Using fixkick’s Full OBD2 scan info, some of the values look OK, and some have me scratching my head, as I don’t really know what all the parameters are indicating, and the manual does not explain what each PID is showing. I have done several engine runs with the scanner connected while learning the scanner and then generating the aforementioned data file, but it has not yet thrown any DTC’s, other than the ones I have intentionally caused by disconnecting MAF and TPS connectors.
That brings me to drive cycles – I have not tried capturing any live data while driving since driving it with the big stumble is sketchy with normal or heavy traffic. The only driving I have done with the vehicle was the 15 miles to get it home, late in the evening. The FSM says that “A driving cycle consists of two parts, engine startup and engine shutoff.” Is driving the vehicle the only way the ECU will be able to generate any DTC’s?
THE ONLY ERROR HERE IS NO TRANSMISSION STATED.
Similar to Ropadopa, I recently acquired a 1996 X90 – I got mine from a co-worker, and it has what appears to be a pretty good misfire when the throttle is applied quickly. He had been troubleshooting it for some time, and finally gave up after he could not resolve the issue. I had been looking for a G16B to put in my Samurai, so he sold me the X90 for next to nothing to get it out of his garage. The car drove fine for approx. a year after he got it, but about six(?) months ago it started acting up with the misfire condition. Just short of 90K on the odometer. Rebuilt/salvage title.
Feathering the gas pedal will allow it to rev to redline with no issues, but anything more than a moderate press on the pedal results in the misfiring condition. It will eventually stumble up to about 3000 RPM and then rev up normally. If the pedal is fully floored at idle, it will pretty much chug and burp until the pedal is lifted. The exhaust smells like it is running rich when misfiring, but it is not putting out black smoke. The fast idle at cold start works normally, but at idle when warm, there is a slight intermittent misfire.
Reviewing the forum posts for similar conditions here, and consulting a borrowed FSM from the previous owner (PO), this is what I have checked so far:
Compression check (warm eng, WOT): #1 – 185#; #2 – 195#; #3 – 187#; #4 – 186#
Engine vacuum is 21” Hg and steady;
Installed Bosch cap, rotor and wires;
Ignition timing with freeze jumper is 6 deg., crank pulley bolt is tight, but I did not verify cam timing marks;
No cracked exhaust manifold tubes;
PO installed new cat;
FPR testing: Key on – 39#; Idle – 33#; Key off – 31.5# and will hold it for well over one minute. Applying 26” Hg to FPR nipple shows 31# (should be 21#?) Have not done shunt test (pinched vacuum line to FPR).
EGR valve responds (tries to stall engine) when diaphragm is pushed, FSM live EGR test shows normal ops;
Removed and cleaned dirty throttle body, which helped, albeit minimally.
The PO had a low dollar code reader and said that the car had generated a P0300 awhile back. I bought a Autel Autolink AL619 scanner as it will read some live data. It showed no DTC’s stored, or pending. It shows that the TPS appears to be working normally with key on, engine off. Using the live data feature, I generated this readout using all PID’s available (see attached file).
The data can be downloaded and printed out as a text file and it is output in ‘frames’, which are cumbersome to compare – for me - with all the pages generated. I entered all of the data into the attached MS Excel file for easier review. RPM is highlighted in a red font, and I highlighted “Frame 15 & 16” where the induced misfire condition was taking place.
What the data shows is 15 seconds at idle, 15 seconds at 1500 RPM (trying my best), 15 seconds at 2500 RPM, 15 seconds at 4000 RPM, then 15 seconds to stabilize at idle. Then 10 seconds with the gas pedal floored, causing the misfire (frames 15 & 16), then a final 15 seconds to stabilize at idle again.
Using fixkick’s Full OBD2 scan info, some of the values look OK, and some have me scratching my head, as I don’t really know what all the parameters are indicating, and the manual does not explain what each PID is showing. I have done several engine runs with the scanner connected while learning the scanner and then generating the aforementioned data file, but it has not yet thrown any DTC’s, other than the ones I have intentionally caused by disconnecting MAF and TPS connectors.
That brings me to drive cycles – I have not tried capturing any live data while driving since driving it with the big stumble is sketchy with normal or heavy traffic. The only driving I have done with the vehicle was the 15 miles to get it home, late in the evening. The FSM says that “A driving cycle consists of two parts, engine startup and engine shutoff.” Is driving the vehicle the only way the ECU will be able to generate any DTC’s?
THE ONLY ERROR HERE IS NO TRANSMISSION STATED.