Ignition troubleshooting issue...

[Todd]

I changed my rotted muffler on my '83 280ZXT with a Dynaflow Turbo muffler two weeks ago. The car idles much smoother and has the power on demand, where as before it was as if I was driving around with my emergency brake on. It seemed like the engine wanted to go, but was restricted. The muffler was full of rust.

 

The next day, I went to go somewhere in my car and after warming up. it died. It would crank over, but wouldn’t fire. A little later, it would start and ran fine. But then it would die for no reason. And then a little while later it would start again. I am thinking to myself, is this related (O2 Sensor, MAF Sensor, Fuel Pump, etc.) or is it just a fluke that this occurred after I changed the muffler.

 

 

I had troubleshot the ignition system down to what I thought the problem was the power transistor on the side of the coil. If I put a heat gun to it, after 30 seconds, it would die.

 

I ordered a new one ($137 at Carquest), got home, started my car and drove it into my garage. Pulled the coil, pulled the powertransistor and replaced it with the new one.

 

 

It hasn’t started since. Even with the old original one, or the used one I had.

 

I have my 5V pulse coming from my optical encoder in the distributor to the ECCS, and am getting a 12V to 7V transition on (blue wire on (–)) the primary side of coil.

 

The coil measures .8 ohm on the primary and 8.9K ohm on the secondary. The spark plug wires each measure approx 8K. I get no spark.

 

Any thoughts as to what would prevent the coil from firing?

[roger.svoboda]

If the car wasn't running how do you know the power transistor was dead? Have you checked the fuel pressure? Need fuel, air and fire to make em work. any one of the three missing and no go. fuel delivery problems seem more common than ignition woes. Checked all your connectors under the hood for corrosion? Don't get so focused on one idea that you neglect other things. Check the air intake system for a mouse nest. is the afm working?

[Todd]

If the car wasn't running how do you know the power transistor was dead? Have you checked the fuel pressure? Need fuel, air and fire to make em work. any one of the three missing and no go. fuel delivery problems seem more common than ignition woes. Checked all your connectors under the hood for corrosion? Don't get so focused on one idea that you neglect other things. Check the air intake system for a mouse nest. is the afm working?

 

The 280ZXT is my daily driver, it has been running fine up till I changed the muffler...then for some reason, I get no spark (verified by pulling plug wire and using spare plug to see if there is any spark across the gap).

 

I haven't "checked" the fuel pressure with a gage, but when I changed my fuel filter in the midst of troubleshooting.......high pressure fuel sprayed everywhere. I will take my friend up on borrowing his fuel pressure gage setup.

 

I have checked all my connectors for continuity, cleaned and repaired any questionable ones.

 

I had pulled the MAF, checked continuity and cleaned it up. No rats nest there. However, I would like to remove the original 10 pound air cleaner and replace it with a K&N.

 

I checked for continuity on my fuseable links, temp sensor, antiknock sensor, O2 sensor....etc.

 

 

I have been reading the blogs and two things jump out at me that I am unsure of: The green light on the ECCS (ECU) and the wires that lead into/from the fuseable links. I seen one blog where the wire leading from the fuseable links was broken that caused the same described problem.

 

Thanks for your insight.

[woldson]

Believe it or not, newer cars are sensitive to welding. You might of had a case with yours that "tanked" an electronic compodant that was getting old anyhow. Hopefully it is not you cpu.

[Todd]

Believe it or not, newer cars are sensitive to welding. You might of had a case with yours that "tanked" an electronic compodant that was getting old anyhow. Hopefully it is not you cpu.

 

I checked the ECU (CPU) for the green light, it was on when the key was in the on position. Hopefully the MIG welder didn't take out my electronics.

 

I checked the fuel pressure, it has 40psi when the pump is pummping. 38 psi after it shuts off. 30 psi in the morning after sitting all night.

 

Now its time to check the wires individually.

[roger.svoboda]

have you looked inside the dizzy for broken parts. Do you get spark from the coil wire to frame thus bypassing the rotor and cap. Noid light on the injectors will verify they are getting pulse. You seem to know what you are doing electrically. Pull the cover on the ecu and look for blown components. CAn you smell raw fuel at the exhaut end? If you do then pretty sure you got fuel but no fire. Easy way to change the air filter is to buy the kit from msa but pricey. I took a 3" exhaust elbow and welded a bracket to it for support to a convenient screw below it. then just add the K&N after that. this is a pic of the msa kit on my 83na. I put the homemade rig on an 81T. I bought the msa thing when I first started with z's then realized I'd been sold something at a really good markup. If you look at K&N site they had a calculator to determine size of filter needed given engine rpm and displacement. That set cost me like $30 and I think the msa one was excess $100

 

I kinda think something died conincedentally with the muffler install but????. Did you weld the muffler on or have it done? Whenever you weld on car have your ground wire as close to the welding area as possible.

[Todd]

have you looked inside the dizzy for broken parts. Do you get spark from the coil wire to frame thus bypassing the rotor and cap. Noid light on the injectors will verify they are getting pulse. You seem to know what you are doing electrically. Pull the cover on the ecu and look for blown components. CAn you smell raw fuel at the exhaut end? If you do then pretty sure you got fuel but no fire. Easy way to change the air filter is to buy the kit from msa but pricey. I took a 3" exhaust elbow and welded a bracket to it for support to a convenient screw below it. then just add the K&N after that. this is a pic of the msa kit on my 83na. I put the homemade rig on an 81T. I bought the msa thing when I first started with z's then realized I'd been sold something at a really good markup. If you look at K&N site they had a calculator to determine size of filter needed given engine rpm and displacement. That set cost me like $30 and I think the msa one was excess $100

 

I kinda think something died conincedentally with the muffler install but????. Did you weld the muffler on or have it done? Whenever you weld on car have your ground wire as close to the welding area as possible.

 

I don't get any spark out of the coil. I think I have a bad connection somewhere between the blue wire coming from the ECU and where it plugs into the power transistor (ignition module on coil). I ohmed it out late last night and was getting 24K Ohm. It should be a direct short if you look at the schematic....unless I have the wrong blue wire. Further diagnosis tonight will help answer those questions.

 

I looked inside the dizzy and the ecu, nothing out of the ordinary. I have verified that I am getting a 5V pulse from the dizzy.

 

I did have the muffler welded on, I helped Jimmy hold it in place as he welded it. It must be a coincidence that I had an ignition problem after I had a new muffler installed.

 

Thanks for the insight on the air cleaner, I have the K&N filter but need the 3" tube. I have a resource, so I will get something drawn up and made.

[roger.svoboda]

measure it before you buy it I think the 3" was for the turbo. Check the size on the n/a it might be like 2.5" YOu could just jump a signal to the base of the transistor and see if generate a spark. Sounds like you are on hte right track anyway. You should have +12 to the collector from the ignition thru the primary and then to the transistor and the emitter grounded. jump some volts to the base and it ought to kick it. Maybe something happened to the mounting socket. Or just not coming thru the ignition switch. Seems other have had that problem.

Edited March 5, 2010 by roger.svoboda

[FricFrac]

I checked the ECU (CPU) for the green light, it was on when the key was in the on position. Hopefully the MIG welder didn't take out my electronics.

 

I checked the fuel pressure, it has 40psi when the pump is pummping. 38 psi after it shuts off. 30 psi in the morning after sitting all night.

 

Now its time to check the wires individually.

 

 

Hmmm Tectronix scope, Fluke DMM, Kim Tuff wipes and an alcohol squeeze bottle..... Electronics tech? ;P

[Todd]

Hmmm Tectronix scope, Fluke DMM, Kim Tuff wipes and an alcohol squeeze bottle..... Electronics tech? ;P

FricFrac, I wouldn't go so far as to say that, when I can't seem to fix my issue without having someone else fix it for me. But, yes...I do have some tools and Electronics Tech/Eng experience.

 

I pinned out every connection, relay, etc. only to find that I am not getting a signal from my ecu to tell my powertransistor to fire. I looked over the ECU and didn't find anything burnt. I ohmed out the transistor in circuit that sends the signal to the powertransistor, it wasn't open or shorted.

 

I put the ECU back in, but before I hooked everything up, I reseated some connectors in the area and tried to pull out the dash (speed sensor that I want to get to). I hooked up the ECU and tried to start it. It started! Then I remembered I had the garage door closed, so i shut it off.

 

When I try to start it again, it doesn't fire.

 

I am close! Oh, so close. There is hope.

[Todd]

I thought I might of had an issue with the Throttle Position Switch, so I checked it out and found that 0 ohms at idle was actually any where around 50 ohms and an open when depressing on the throttle actually was 5Meg. I got the new switch and it checked out 0 and infinity respectively.

 

I read where if you don't have a good signal coming from the TPS, you won't start your car.

 

The new TPS didn't fix it.

[FricFrac]

I thought I might of had an issue with the Throttle Position Switch, so I checked it out and found that 0 ohms at idle was actually any where around 50 ohms and an open when depressing on the throttle actually was 5Meg. I got the new switch and it checked out 0 and infinity respectively.

 

I read where if you don't have a good signal coming from the TPS, you won't start your car.

 

The new TPS didn't fix it.

 

 

I'm not sure but I think the TPS is taking you down the wrong path.....

 

I would hook that fancy scope up and see if you are getting a signal to the transistor module from the ECU. I think you said you were getting your signal from the Dizzy to the ECU so check to see if the ECU is hitting the transistor.

 

Did I read right that the transistor was $137? I could see $1.37 or a way overpriced one at $13.70.... but $137 is insane unless I'm missing something here.... unless it diagnoses all your electrical problems and washes and waxes your car weekly....

[Todd]

I would hook that fancy scope up and see if you are getting a signal to the transistor module from the ECU. I think you said you were getting your signal from the Dizzy to the ECU so check to see if the ECU is hitting the transistor.

 

I put the old scope on the ECU. The ECU is not sending a signal to the transistor, and I get no activity on the tach. So, I am trying to understand what critical sensors (signals) it must see before it will fire. I found an electronic copy of the 280Z fuel injection manual on line and was hoping it was similar enough to my 280ZX that I could gain some understanding.

280zfuelinjectionbook.pdf

[Ineptitude01]

Ooh, ooh, ooh!

 

This happened to me also.

 

Right after I had taken the ECU out to inspect it. The fact that you got it to fire up after you put the ECU back pretty much confirms what I was thinking.

 

My car was dying randomly, refusing to start, running badly... I replaced the dizzy, AFM, TPS, everything related to the system. Turns out that the wiring on the ECU is kind of lame, in that even when it's pretty clean (5 rounds of foaming contact cleaner) it still comes down to a few millimeters of wiggling that will just kill it.

 

If you haven't done so already, I recommend taking the ECU connectors out, and getting some DeOxit (or similar) on there, then getting a file and veeeerrrrry lightly scraping at the pins to break loose corrosion and gunk. It made a world of difference to both my Turbo and my dad's Turbo.

[Todd]

 

Right after I had taken the ECU out to inspect it. The fact that you got it to fire up after you put the ECU back pretty much confirms what I was thinking.

 

My car was dying randomly, refusing to start, running badly... I replaced the dizzy, AFM, TPS, everything related to the system. Turns out that the wiring on the ECU is kind of lame, in that even when it's pretty clean (5 rounds of foaming contact cleaner) it still comes down to a few millimeters of wiggling that will just kill it.

 

If you haven't done so already, I recommend taking the ECU connectors out, and getting some DeOxit (or similar) on there, then getting a file and veeeerrrrry lightly scraping at the pins to break loose corrosion and gunk. It made a world of difference to both my Turbo and my dad's Turbo.

 

So you gave me some hope and inspiration. Unfortunately after cleaning the ECU pins, it didn't start. I haven't cleaned the connectors pins, but I will this weekend. The pins didn't look real bad under the magnifying glass. Todd

[Todd]

The problem was in the dizzy brains. Picked up a used computer and distributor for $100. Put the distributor in, started right up and has been running great ever since. I think it may have been that small square connector wire harness from under dizzy that goes to round wire harness connector near intake manifold. Geesh this took forever to figure out. Wish I would have had some good used parts to try to start with. Thanks for everyones help. Now on to front end suspension and rear end halfshaft ujoints. Todd Higgins in Idaho.

[woldson]

Congrats! Thanks also for the follow up!

[immjg]

The problem was in the dizzy brains. Picked up a used computer and distributor for $100. Put the distributor in, started right up and has been running great ever since. I think it may have been that small square connector wire harness from under dizzy that goes to round wire harness connector near intake manifold. Geesh this took forever to figure out. Wish I would have had some good used parts to try to start with. Thanks for everyones help. Now on to front end suspension and rear end halfshaft ujoints. Todd Higgins in Idaho.

 

I believe I have a similar problem. My car will run for for a awhile until it gets hot, and I loose my signal from the dizzy.

Where did you find the dizzy brains, I'm not having much luck finding one at a reasonable price.

 

Thanks

Malcolm

[Todd]

I believe I have a similar problem. My car will run for for a awhile until it gets hot, and I loose my signal from the dizzy.

Where did you find the dizzy brains, I'm not having much luck finding one at a reasonable price.

 

Thanks

Malcolm

 

The dizzy sends out two signals, a 1 degree and a 120 degree signal. You won't run without both. It took me forever to figure that out. I saw I had "a signal" from the dizzy and was thinking that wasn't the problem. I could nail that problem now! It would have been easier to troubleshoot if I had a spare dizzy laying around. When i found a guy with a parts car, I bought the computer, dizzy and center console for $120. I went back to buy more parts and he sent it off to be crushed! AAAAAAaaaaaaaarrrrrrrrgggggggggghhhhhhhhhhhhhhhhhhh! I called the recycle place and its "gone".

 

I think there are other years of ZX's that you can get your dizzy from. Someone, somewhere has another parts car.

 

I just lost my heater control valve a couple weeks ago, that was a mess. I am going to clean up all the duct work before I put it back together. The dash is easy to remove, 4 screws across the top, 6 small bolts across the bottom, speedo cable and a few electrical connections (8 or so), two bolts for the steering column and the dash comes in and out that easy. I put my stereo back in last night as it sucks not having tunes going to and from work in Boise.

 

Call Oliver at Z specialities in Washington, he checked out my ZX brain. He has alot of parts, awesome guy to know. www.zspecialties.com

 

Later,

Todd

[immjg]

The dizzy sends out two signals, a 1 degree and a 120 degree signal. You won't run without both. It took me forever to figure that out. I saw I had "a signal" from the dizzy and was thinking that wasn't the problem. I could nail that problem now! It would have been easier to troubleshoot if I had a spare dizzy laying around. When i found a guy with a parts car, I bought the computer, dizzy and center console for $120. I went back to buy more parts and he sent it off to be crushed! AAAAAAaaaaaaaarrrrrrrrgggggggggghhhhhhhhhhhhhhhhhhh! I called the recycle place and its "gone".

 

I think there are other years of ZX's that you can get your dizzy from. Someone, somewhere has another parts car.

 

I just lost my heater control valve a couple weeks ago, that was a mess. I am going to clean up all the duct work before I put it back together. The dash is easy to remove, 4 screws across the top, 6 small bolts across the bottom, speedo cable and a few electrical connections (8 or so), two bolts for the steering column and the dash comes in and out that easy. I put my stereo back in last night as it sucks not having tunes going to and from work in Boise.

 

Call Oliver at Z specialities in Washington, he checked out my ZX brain. He has alot of parts, awesome guy to know. www.zspecialties.com

 

Later,

Todd

 

Thanks for the info. I got a scope out tonight and verified I was loosing the 120 degree signal. Put some ice on the bottom of the dizzy to cool it off and bang it came back, well until it got hot again. Never had any trouble with the 1 degree signal. Now to find a camshaft position sensor. Thanks for the zspecialties suggestion, I'll check it out.

 

I have two 1982's, unfortunately the distributors are not interchangeable, one is the turbo at the other a 5speed

 

 

.

 

 

 

Malcolm