1991 Lexus Ls400

[chiquipr]

Hi, I just did a mayor tune up on my 1991 Ls400, spark plugs, wires, cap's & rotor's air filter and fuel filter. I re-checked the firing order and is fine. When I start the car the check engine and track off light goes on and stay on, at idle seem fine and when I step on the gas in park I can feel a misfire at around 2000 rpm or more, when I drive it can't go over 40 mph because it start pinging bad like if it is out of timing. I got the parts from Auto Zone, do you guys think that it may be the cap and rotor. Thank you in advance.

[Rugster]

Hi, I just did a mayor tune up on my 1991 Ls400, spark plugs, wires, cap's & rotor's air filter and fuel filter. I re-checked the firing order and is fine. When I start the car the check engine and track off light goes on and stay on, at idle seem fine and when I step on the gas in park I can feel a misfire at around 2000 rpm or more, when I drive it can't go over 40 mph because it start pinging bad like if it is out of timing. I got the parts from Auto Zone, do you guys think that it may be the cap and rotor. Thank you in advance.

Bad plug/plugs out of box? Gap set right?

Dist. Cap/Rotor not good / not replaced right?

[chiquipr]

Hi, I just did a mayor tune up on my 1991 Ls400, spark plugs, wires, cap's & rotor's air filter and fuel filter. I re-checked the firing order and is fine. When I start the car the check engine and track off light goes on and stay on, at idle seem fine and when I step on the gas in park I can feel a misfire at around 2000 rpm or more, when I drive it can't go over 40 mph because it start pinging bad like if it is out of timing. I got the parts from Auto Zone, do you guys think that it may be the cap and rotor. Thank you in advance.

Bad plug/plugs out of box? Gap set right?

Dist. Cap/Rotor not good / not replaced right?

New plugs out of the box, gap set right. Yes I replaced the 2 Dist Cap & rotors, also the wires. I used NGK Iridium spark plugs.

[eatingupblacktop]

Hi, I just did a mayor tune up on my 1991 Ls400, spark plugs, wires, cap's & rotor's air filter and fuel filter. I re-checked the firing order and is fine. When I start the car the check engine and track off light goes on and stay on, at idle seem fine and when I step on the gas in park I can feel a misfire at around 2000 rpm or more, when I drive it can't go over 40 mph because it start pinging bad like if it is out of timing. I got the parts from Auto Zone, do you guys think that it may be the cap and rotor. Thank you in advance.

Bad plug/plugs out of box? Gap set right?

Dist. Cap/Rotor not good / not replaced right?

New plugs out of the box, gap set right. Yes I replaced the 2 Dist Cap & rotors, also the wires. I used NGK Iridium spark plugs.

Wires oem? Check resistance. Can always put back in the old parts to check the new parts.

[chiquipr]

Hi, I just did a mayor tune up on my 1991 Ls400, spark plugs, wires, cap's & rotor's air filter and fuel filter. I re-checked the firing order and is fine. When I start the car the check engine and track off light goes on and stay on, at idle seem fine and when I step on the gas in park I can feel a misfire at around 2000 rpm or more, when I drive it can't go over 40 mph because it start pinging bad like if it is out of timing. I got the parts from Auto Zone, do you guys think that it may be the cap and rotor. Thank you in advance.

Bad plug/plugs out of box? Gap set right?

Dist. Cap/Rotor not good / not replaced right?

New plugs out of the box, gap set right. Yes I replaced the 2 Dist Cap & rotors, also the wires. I used NGK Iridium spark plugs.

Wires oem? Check resistance. Can always put back in the old parts to check the new parts.

I got all the parts from Auto Zone. If it was easy to R & R the new parts with the old ones again I'll do it 10 times but is not. The main intake air hose have some cracks Do you think that would cause the problem? Thank you.

[ggemigniani]

yes, if the hose between the air filter and throttle body has any holes or loose clamps the engine will run poorly. This is true for all Toyota fuel injected engines.

[curiousB]

I got all the parts from Auto Zone. If it was easy to R & R the new parts with the old ones again I'll do it 10 times but is not. The main intake air hose have some cracks Do you think that would cause the problem? Thank you.

Easy or not you need to get back to stable footing. You imply the rough running is as a result of the "tune up". Then I would suggest reviewing what you did before you go chasing after other theories. Pinging implies unburnt fuel, unburnt fuel suggests misfiring, misfiring suggests ignition, ignition, well that was touched.

Just try disconnecting one plug at a time at the distributor and see if the roughness stays the same (ie doesn't get worse) then its a good bet that wire or plug is bad (or its arcing to chassis).

Small cracks in air intake could cause rough idle but wouldn't likely explain higher throttle issues you see.

This sounds like ignition to me. I'd retrace your steps.

[SLORICK]

Should he check timing with a timing light?

Could a vacuum hose have come undone?

Duct Tape should fix anything.

[dpellet]

Do check all vacuum lines. It's very easy to get one pinched or twisted and restrict pressure to the appropriate valve or sensor. I had one of mine twisted, took me forever to trace it.

[VBdenny]

I wouldn't pull off the plug wires to check and see if they fire rather use one of those laser thermal temperature detectors. In your case the very first thing I would check are the rotors. I used the NGK plugs with no problem and I did check the gap and all were exactly on right out of the box.

[chiquipr]

Thank you for all your input and replies guys. Yesterday and today going and coming back from work the car is jerking on and off too like if it was running out of gas.

[curiousB]

Thank you for all your input and replies guys. Yesterday and today going and coming back from work the car is jerking on and off too like if it was running out of gas.

Then I would check:

1) Incorrect wiring of cylinders to distributor (have a couple swapped)

2) Bad spark plug wire (open circuit or high resistance)

3) Wire arcing to chassis (pinched wire or damage insulation layer)

4) Bad plug

I wouldn't spend much time on a vacuum leak as that would tend to be a problem at idle and less so at more open throttle positions. I could be crank position sensor but if you didn’t touch that it would seem strange that would mysteriously fail at the time you worked on other parts of the ignition.

[RDM]

Although these replies are all good, why not just pull the codes since the check engine light is on? That will narrow down your search path considerably.

[chiquipr]

Hi guys, i just want it to give you an update. I reinstalled all the old parts since car started pinging and jerking more and more but still the same, I guess that I'm gonna have to take it to the dealer for a diagnose.

[RDM]

You can't pull the codes yourself? There's a good tutorial on lexls.com.

[chiquipr]

Yes RD, i just pull the codes and I'm getting Code-13 witch is RPM Signal No.2. So from witch Distributor the signal No.2 come from, driver or passenger side? Thank you.

[wuzzy1]

Hi, I just did a mayor tune up on my 1991 Ls400, spark plugs, wires, cap's & rotor's air filter and fuel filter. I re-checked the firing order and is fine. When I start the car the check engine and track off light goes on and stay on, at idle seem fine and when I step on the gas in park I can feel a misfire at around 2000 rpm or more, when I drive it can't go over 40 mph because it start pinging bad like if it is out of timing. I got the parts from Auto Zone, do you guys think that it may be the cap and rotor. Thank you in advance.

I'll bet a dollar to a doughnut that you have a wire crossed.

[chiquipr]

I wish that it was just a crossed wire, Anyhow, I couldn't get back to my car until today due to my job. Anyway today I removed the cam sensor #2 and there is no signs of pinched wire and/or bad connection, I also checked continuity and is fine. You guys think that is the cam sensor it self? Thank you in advance.

[williamb82]

id double check the firing order. 2 wires swapped can cause all sorts of issues. but id check the wheel the cam sensor reads from as well. if the sensor checks out on the meter a wire may have broken inside the harness when you moved it. they are old and can get very brittle.