Timing is waaay advanced help!

[frapjap]

Alright, the story: 1990 Chassis, 95 ka24de. Runs great, idles fine, accelerates and operates soundly, good gas mileage, can race, etc... Went to check the timing to finish up a tune up, and had a solid 20 degrees; Like we should. Then I remembered we have to disconnect the TPS to get base timing and be sure its all in line. So, I disconnected it, and time it out, WHAM, I'm about 20 degrees advanced!!! Idle is about 1500 rpm now. I found this really odd. I then adjusted the Idle air contol and I'm not getting any results, so I rotate the distributor, still nothing desirable. I decided to leave it alone, and just reconnect it all and go on my way home. Ran fine, idled like usual, no pinging, knocking, leaning out, normal mechanical shape. Any ideas on what is wrong? I also have a leaky brake booster, but I don't think it would contribute to what I am observing. All marks and links are lined up perfect... HELP!

[s13sr20chris]

20 degrees advanced of your 20 degree target with tps unplugged? so your saying with tps unplugged you have like 40 degrees of base timing? thats no good. unplug tps and set base timing to what you want via turning the dist(engine warmed up FULLY). trying to set the idle will frequently not have any effect unless you unplug the tps.

[navysnail]

leaky brake booster will cause your car to idle higher as it is introducing air into your engine like the idle air controler, but it is not going through the MAF

[frapjap]

Essentially, yes, I'm at 40 degrees advanced timing. I will try what you say to do and turn the distributor with the tps unplugged, I'll post results very soon. I will also pull my vaccum line from the brake booster and plug it up to a solid vaccum and see how much it affects the idle. Thanks!

[frapjap]

Okay, here are the results via instructions from SR20CHRIS and 240KID: --- TPS DISCONECTED:---1) Idled between 1-1500 rpm @ ~40* ADVANCED. 2) Rotated distributor to 20*. Idled at 1200-1300rpm. Exhaust "put, puts"3) Disconeect brake booster and pluged it. Timing ran between 10-20*. Machine gun sound from exhaust at idle.2 B) sometimes car will idle between 7-800rpm at this point timing is adusting itself from 20-22* (advancing and retarding itself slightly) Until gas pedal is tapped, then resumes idleing at 1200-1300 again.

--- TPS Reconnected, timing set by distributor to 20*---1) 900-1000 rpm at idle.2) Timing between 20* and 15* 3) Plugged vaccum line @ brake booster, got less sparatic movement in timing. Idle was at 7-800 rpm, sound from exhaust was "put, put, put REV, repeat."***HOWEVER***Exhaust does NOT sound this way when the timing gun is disconected. It is a solid idle between 8-900 rom or 9-1000 rpm. Any ideas?

Also, on taking off the valve cover, the Intake Cam is Orange, and the Exhaust is Green. Is this correct? It is a 1995. Upon slightly closer inspection, the exhaust cam lobe on cyl. 1 seems to be slightly higher than the intake lobe. I *think* its supposed to be the other way around?
Modified by frapjap at 12:45 AM 12/19/2004

[s13EastTN]

If it was fine before hand and ran great, I wouldn't even mess with it. Honestly if its not pinging at 40 degrees then you are probably reading it wrong, or its being retarded for some reason.

[frapjap]

Problem is, I'd like it to be dead on, because until it is I can't use my nitrous.

[DAEDALUS]

What controls ignition advance? Is it centrifugal and/or vacuum?

[DAEDALUS]

Nevermind. The ECU controls everything, I just checked the manual. Older ignition systems have mechanical and/or vacuum-controlled ignition advance. Idle speed should be 650 RPMs. (RPMs affect timing.) Doubt the difference would cause 20* timing change, but...?

[s13sr20chris]

well im afraid we need to take some more measurements.do you have a multimeter? we need one.how many plugs are on the tps? one or two?i need you to verify that the closed throttle position switch is closed at idle if you have one. this would be the second connector. more on this if you have it.

maf voltage? please measure voltage between each maf wire and ground and post results. to do this with engine running you must back probe the connector. take sowing pin(i use a t-pin) and stick it between wire insulation and the rubber boot inside the connector. it needs to make solid contact with the terminal. dont worry you wont break anything.

tps voltage? with or without closed throttle position switch please do the same here as with the maf connector.

coolant temperature sensor resistance? this must be unplugged with engine off. do it once cold and once hot please.

vaccum reading at idle and a 2000rpm?

what do the plugs look like? clean? nasty?

[ILikeMy240sx]

You said that your idle with TPS unplugged was 1~1.5K Try adjusting the idle to 700 RPM before measuring the timing.

[frapjap]

[QUOTE=s13sr20chris]well im afraid we need to take some more measurements.do you have a multimeter? Yup, I can get a hold of one

How many plugs are on the tps? one or two? Inside the connector there are 3 termianls. Plugs coming off of the same portion of the harness, 2.

i need you to verify that the closed throttle position switch is closed at idle if you have one. this would be the second connector. more on this if you have it. Is this the plug/sensor, or the thing that I can adjust my idle with is when I use a Philpps head screwdriver?

maf voltage? please measure voltage between each maf wire and ground and post results. to do this with engine running you must back probe the connector. take sowing pin(i use a t-pin) and stick it between wire insulation and the rubber boot inside the connector. it needs to make solid contact with the terminal. dont worry you wont break anything. I'll post thsoe results as soon as possible.

tps voltage? with or without closed throttle position switch please do the same here as with the maf connector. Same as above

coolant temperature sensor resistance? this must be unplugged with engine off. do it once cold and once hot please. Same as abovevaccum reading at idle and a 2000rpm? Don't believe that I have anything to measure this... : (what do the plugs look like? clean? nasty? Plugs look great

[DAEDALUS]

More info? You found the volts DC setting and the ohms setting? Are the probe wires in the right sockets? Tell me what you want to do and I can post a pic after work if you don't have it figured out by then.

This might help:

http://www.multimeterwarehouse...r.htm

[510SX]

Alright, I'm stupid, someone help me use a multimeter, please?

hmm, I read you previous posts. What kind of timing gun you have?Just to double check, some timing gun have advance turn knob. If you set your advance knob to 20 degrees and you beam at the pulley. You will see 40 degrees at the pulley.

May be the car was dead on 20 deg, right at the beginning. just your timing gun set wrong.

[frapjap]

Daedalus, I have an Autoranging Multi-meter, minus the holes that the one in the website has. Its just a dial with the various symbols.

I want to test the voltage in the points specified above (tps, maf, cts)

510sx, its a cheapy light with an alligator clamp and spring from autozone. No knob here.

[DAEDALUS]

hmm, I read you previous posts. What kind of timing gun you have?Just to double check, some timing gun have advance turn knob. If you set your advance knob to 20 degrees and you beam at the pulley. You will see 40 degrees at the pulley.

May be the car was dead on 20 deg, right at the beginning. just your timing gun set wrong.

The knobs are usually dial-back knobs, so if the timing's at 20* and the dial's at 20*, the flash will fire at top-dead center (0*).

[DAEDALUS]

Ohm symbolVolts DC symbol

Do these match? Set the selector to the one you want to measure. Never try to measure resistance (ohms) when the circuit is powered up. Measure voltage with the key on (or car running). Measure resistance with the key off or better yet with the battery disconnected.

[s13sr20chris]

[QUOTE=frapjap][

How many plugs are on the tps? one or two? Inside the connector there are 3 termianls. Plugs coming off of the same portion of the harness, 2.QUOTE]

ok, if you have two connectors then one of them is for the closed throttle position switch and wide open switch. the other is for regular tps value. i will bring home the bulletin so we can set it RIGHT. heh, nissan even had trouble for a while trying to figure out how to do it.

[frapjap]

Awesome, I appreciate the help so much! Anyway, I've got which is which sorted out, as far as what is closed and open throttle (or else I wouldn't hear a 'click' from my nitrous selinoid.) Hope to hear from you soon!

[s13sr20chris]

ok, the spec on yours is still measured the old way. you want to find the signal wire(goes from 0-5volts closed to open). then adjust tps with engine hot to get .4 v there with throttle closed. its the newer ones that have the new procedure with the feeler gauges.

[frapjap]

Chris, got those last measurements-

Voltage TPS Top connector, left to right, SHUT 5.1, 4.58, 28

Voltage TPS Top connector, left to right, WOT 5.08, 4.5, 32.6

Voltage TPS Top connector, left to right, @ IDLE 5.08, 4.5, 23.6

Voltage MAF sensor, right to left 12.3 41 491

Modified by frapjap at 9:59 PM 12/20/2004

Modified by frapjap at 10:00 PM 12/20/2004
Modified by frapjap at 10:01 PM 12/20/2004

[s13sr20chris]

ok, that looks like a tps issue. you have 5v which is sensor voltage. then you have signal return to ecm which was like 4.5v or so whether at wot or completely shut(bingo!). the last should have been the ground but i cant tell. you give 28, 32.6, and 23.6 respectively for the last wire. surely it did not have that many volts! maybe it was that many milivolts? if it was millivolts then thats great. in fact that would be the ideal voltage drop.

ok, if that was milivolts or something that gives you a good ground then you have bad tps. this is easy to find out. put one probe on your tps power(left wire) and one on ground(right wire) and see how many volts you get. doing voltage drop as above is more accurate but i fear the units may be difficult to figure out.

if you confirm the tps is the issue...try removing it and operate the metal spring loaded thing by hand. check to see if you can get the proper voltage sweep with it plugged in by hand. the sweep would be from about .4v to 5v. i have seen a few tps sensors that were installed wrong and moving the throttle did not move the metal thing. however, they usually were at the low end of the spectrum so this would be rare.

[frapjap]

Alright, the measure I got from the left and right terminals was between .2 millivolts and .4 millivolts. That otehr was in millivolts too, I missed the miniture 'm' on my digital screen.

Where is the spring thing located?
Modified by frapjap at 9:53 PM 12/21/2004

[s13sr20chris]

connecting the left terminal(that was at 5v earlier) to the left terminal(was in the mv range) only gives you .2-.4 mv? thats no good. you should have full sensor voltage(5v) available there.

the spring is inside the tps. when you remove the tps you will see a metal thing that will rotate. it is spring loaded. it is moved by the throttle.

[frapjap]

ALRIGHT! Sorry for the delay, x mas holidays and all! Yes, the spring dealy stopped working so the ecu thought I was at WOT all the time. It was basic advance that the motor takes. BIG THANKS to you SR20CHRIS!!! I really appreciate it!

[s13sr20chris]

no prob<tips hat>