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Ok so if ALL coils are getting +12... then check the low side wire ( not the ground ) on the coil pack...

If the car is " idling " the low side line will flicker on the test light... no flicker... no spark signal..
Which is PTU..ECM or CAS...

If it IS flickering... bad coil...

Mike
 

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Discussion Starter #82
ok im going to have to wait to get the timing gun/light im a little low on funds. for grins though now that the car is at least idling on its own.. i went ahead and tested again for codes.

im getting a 13, 14 and 53, if remember one is a coolant temp sensor, ones a speed sensor and ones something to do with an 02 sensor

because i think some of them are from before the contacts were recleaned, ive pulled the battery and am going to give it 30 mins or so, then restart the car, let it run for a few and retest for codes

thank you for all your help so far i really appreciate it
 

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You're learning fast. well done! Maybe if you go through six more Z's and finally do a TT swap, someday you can be a moderator!
 

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11: crank angle sensor circuit
12*: air flow meter circuit
13*: engine coolant temp. sensor circuit The VERY first one I asked for you to inspect!
14*: vehicle speed sensor circuit ( not important right now... did your speedo work before?)
21: ignition signal circuit
26*: boost pressure sensor
31*: ECU
32*: EGR function
33*: exhaust gas sensor circuit (left)
34: detonation sensor circuit
35*: exhaust gas temp. sensor circuit
42: fuel temp. sensor circuit
43*: throttle position sensor circuit
45*: injector leak
51*: injector circuit
53*: exhaust gas sensor circuit (right) Check the connector for the O2... it's probably flooded with raw gas!
54: signal circuit from A/T control to ECU
55: NO malfunctions in the above
 

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Not TIMING light ( but that would work too... ) just a 12 volt test light!

Mike
 

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Discussion Starter #86
ok how about a 12V led that i made to retreive codes from my old 944Turbo? that works off 12V would that work?
 

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YOu need a test light that will draw current.. an LED cannot pull enough current to be REAL useful...

A tail light with some wires soldered up would be better....

Mike
 

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Discussion Starter #88
that i do have! let me throw some wires on a 12V tail light bulb and i can try it out.

This is my 3rd Z, i have a 72 240Z (automatic that wouldnt use first gear) and an 81 280zx 5 speed (miss that car) so ive had a few Z's, a 928S, an 83 911SC, an 88 944 turbo. Im pretty good with my hands and with a meter, soldering, all that stuff, but i kind of have to be careful with spending as i lost my computer job the day after my son was born. so if we can use a light bulb to test, then ill set it up

thanks again
 

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OK I get it.....
Male clip lead on one end, pokey SHARP probe on other additional points!

Make no assumptions on this car based on your prior wrench experience.... this one is VERY different...

Mike
 

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Discussion Starter #90
ok i must be doing something wrong. i tested my light setup by hooking it up to the battery and the bulb came on. im hooking the positive of the bulb to the far left of the 3 on the coils wire, and the black to the far right which i checked and is the ground. im not getting any lights, so i checked another coil that i know is working and no lights there either.... am i doing this right?
 

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Ok ready
The center pin ( on the coil pack ) is the control from the PTU.

Little blacks go to chassis ground. BIG.center wires are for coil primary low side.

The BIG blacks are the HOT for the coil secondary.+12

So you want your test light between the BIG BLACK AND THE CENTER PIN on the coil pack connector...

So your hanging your test light across the coil primary..... and you will see it a dim flicker if the PTU is switching

the flash will be more intense as your cranking...Not like a strobe... but bright, not as bright,bright.. etc..

If there is NO LIGHT.. the PTU is OPEN.. if the light is stuck dim... it may not be getting an input pulse
and if it's BRIGHT all the time.. THE PTU is shorted..

The PTU switches GROUND....

Mike
 

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Discussion Starter #92
Update:

Changed the oil and filter
Replaced dead fog light
Replaced Air Filters
ALSO got it titled and tagged so its actually legal to test drive it now!
Also picked up REAL contact cleaner... i was using WD-40 before. havent had a chance to spray anything other than a few connectors i will do them all tomorrow

Ok as far as driving it goes, well its slower than my ford ranger, but thats ok, its still only running on 3 cylinders, and doesnt like to idle very well when the headlights are on, or the fans, or the ac, or well anything that pulls from the battery

anything over 40mph and things begin shaking. The brake rotors need to be turned. As soon as i touch the brakes at speed the front end starts shaking . It also sounds like a VW bug or an old 911. Sounds like the average Flat 6 or flat 4. Havent figured that out yet

So a balance and alignment may be in order

anyway back to our 3 cylinder issue.. it accelerates smooth, just not very fast. im going to remove all the connectors tomorrow, and spray everyone down with contact cleaner, let them dry out and reassemble.

one thing it does do very well though is turn; there doesnt appear to be any lateral lean what so ever. its like its glued to the road

reminds me of the 944T :-D

is anyone else in the northern va area i could use some help tomorrow turning my go kart into a z again and am still stumped on te 3 cylinders not firing
 

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Did you do the test light test?

AND??

maybe reseat the PTU cables?AGAIN?

Mike
 

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Discussion Starter #94
UPDATE

ok here is what ive tried to pin down the problem. Saying that all the coils and stuff are good on the driverside of the car, i moved 1 of the coil packs from the working side of the engine, to the side that isnt working, and moved one of the coil back that wasnt working to the good side. car started up immediatly, so its not the coil packs... so were down to fuel injectors, connectors, and wiring... aside from CAS and PTU
 

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You've confirmed that there is no ground pulse going to ANY of the coils.... in that bank, visually with the test light??

Have you removed ALL the harness on the PTU and cleaned it?
Have you ohmed the wiring between the coil pack & the PTU on that side??

Forget injectors ( at this point ) work on spark first...

What I would do at this ponit.. is mark the location where the CAS is mounted on it's frame ( this is like marking a distributor )..
This way you can use it as a test device without cranking the engine...

In the FSM... with Key on... If you spin the CAS input shaft, it will fire the coilpacks & you can hear the injectors click.

I know your on a budget.. do you have a wrecking yard near you?

Mike
 

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Discussion Starter #96
Update

Ok bit the bullet and took the car to one of the guys in the local Z club that specifically deals with 300zx's. he tested the ptu and cas sensor and said that wasnt the problem. all the fuel injectors on the driver side were bad, testing at approx 50ohms.... not good. He went ahead and drimmeled out the middle one and replaced it, and sure enough were upto running on 4 cylinders instead of 3. so we have progress i just wasnt testing them correctly. The engine now sounds unbalanced due to 3 running on 1 side and 1 running on the other side, but its alot snappier than before. Soon as i make some more money im having him finish the last 2 and it should run alot better and run without sounding like a boxer engine. I might have a rear main seal leak there are no marks on the ground, but the clutch appears to be slipping now in 3 and 4th gear. Hopefully the clutch just has some air in it and rebleading it will help. it wasnt slipping when i first drive it, but maybe the extra power is allowing it to show up
 

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Ok well that's interesting....

So with 4 cylinders running your slipping?? in an N/A!!

In 1st where does the clutch engage... 1/2 way up, all the way up, varies if hot or cold??

Mike
 

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there MIGHT be rust on the flywheel but very unlikely. my bet is like vig said if its slipping on a na the clutch is toast..... pressure plate could be weak or clutch fork bent but id put money on the clutch. but if it doesnt slip in 1st or 2nd thats weird
 

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Or a misadjusted slave... or oil soaked clutch ( from bad crank seal ) ....
Many factors....

Mike
 
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