No fire No starting issue!!!!

hermesbooking · 10-08-2008, 04:20 PM

OK, well I am on the last limb with my car! I am really thinking about parting it out if I can't get the stipid thin started. I have a few other posts and have went through several trouble shooting checks, from the sensors to the battery, fuse box, everything. Well I got it started the other day with starting fluid, let it run for about 10 mins. Turned it off and tried to start again and nothing. Pulled the #1 plug, pluged it into the wire grounded it out and had the wife turn the car over, and no spark, nothing. Did all the checks with the ignition, good, have a new battery, new alternator, new plugs, new cap, new rotor, new coil, everything checks good. Did the checks throught the fuse box on the DME relay and ended up having everything check good. Have good fuel pressure at starting is around 40 psi. When trying to start it, have good power and the starter is strong. Suggestions????? Is my computer shot? I have not had the time or the cash now to send off or get a new one. Somthing I have missed somewhere? Only thinkg I have not checkd is the o2 sensor. While I was running it the other day, i unplugged the sensor to see it there was a diff in the running of the car, and nothing was diff, even at running temp. I am lost. Suggestions welcom???? If yo ugot free long distance, give me a call 325-227-0213 or send me your number and I will call you.

The bad thing about this, and reason it is making me so mad, is I can't find the problem, but I can fix a B220 King Air airplane and get it flying!! Its going to be somehting simple!!!

924Sman · 10-08-2008, 04:45 PM

Try borrowing a ECU and see if the that rules the computer in/out. The AFM is also suspect from what I get out your issue, do the same with a known working AFM. You are in Texas and there are plenty of owners who could possibly bring their ECU/AFM over to rule those out....give it a try!

My bet is the AFM, if they go bad it will never run, the ECU is working so it seems because you do get it fired up.

Dal

hermesbooking · 10-08-2008, 06:15 PM

That is my next step is too send the computer to a friend to check it out. I just got so busy and work and had school, so hopefully I can get it this weekend. I will also look at the AFM as well. Thanks

EMBPilot · EMBPilot's Garage

King Airs are easy, they never STOP running! PT6 baby!

drew1 · 10-08-2008, 09:32 PM

I've seen them fire up then die with the AFM or VAF unplugged.

Looked & saw you have an 86. Not sure what year ign switch changed, but 924 & early 944 switch can go erratic.

If you had to spray ether in it to get it started & running, I would check for vacuum leaks. Those hoses under the intake can be a mess.

hermesbooking · 10-09-2008, 03:35 PM

As for the Vacc system. I replaced the vacc system about 6 months ago with the set up from Lendsy racing. New hose and t fittings. Everything seams to be hooked up and no leaks. I am hoping the switch might be bad? Would that have an issue? I did nto check that out. Thanks Mike

924Sman · 10-09-2008, 03:58 PM

Ignition switch is not a bad suggestion but it started and ran. Switch has 3 modes, off, start and run. If it starts up by the key that mode is ok and it ran for 10 minutes the run mode is also ok so I am not to sold on that suggestion. You also said it cranked with good power so that rules out the start mode You did state you checked the ignition, correct?

The use of starting fluid suggests the A/F mixture is too lean/rich and this is governed in part by the AFM. Taking the O2 sensor out has no bearing as it only comes into play once the exhaust temperature is at maximum. Without it it will run a continous loop and run regardless and throw the lean/rich mix off a bit so it may run a bit sluggish.

One thing I would have a good look at is the J boot! Under the boot there is a port for a metal vacuum line/pipe. If the rubber grommet like section is cracked it will be a problem starting it up. Remove the J boot and turn it over and look for a crack.

Dal

hermesbooking · 10-10-2008, 03:22 PM

Good, that looks like it knocks out the ignition switch! I know my boot is pretty old. I need to replace it. I will need to take a look tonight at the boot. I did spray starting fluid over the boot and all the intake areas when it was running the other day to see if I could find a leak somewhere. It did not studder. Thanks for the help. Mike

924Sman · 10-10-2008, 03:27 PM

Just a note...the spraying you did probably did not reach under the boot. It is pretty concealed and tight little area to reach let alone see with the naked eye w/o loosening the boot and lifting it up a bit.

I would be darn careful spraying starting fluid around a running engine however!!!....FLASH

...Use brakekleen or something else.

Dal

hermesbooking · 10-10-2008, 04:13 PM

I know on the starting fluid. I did it when it was cold first stating up. Was not too smart, but wanted to see if there was a change. Thanks for the info.Mike

hermesbooking · 10-12-2008, 01:24 PM

Forgot to note that when I let it run the other day and turned it off. Tried to start wehn everything was warm/ hot and I was not able to even get a spark out of the #1 plug and grounded it. I have not tried it due to work. Ignition switch a real possibibility??? I am really lost and everything has checked good. I have not checkd the AFM, ignition switch, O2 sensor yet, seams everything else have been checking OK. Mike

AKCJ · 10-13-2008, 11:20 AM

Sounds pretty frustrating.

The O2 sensor has nothing to do with not starting.

You were able to get it started with starting fluid which would indicate a fuel problem and now no spark which would indicate an ignition problem?!

I would definately get a fuel pressure gauge on there so you know if you have it (pressure) or not. If you have fuel pressure that eliminates a variable. Could still not start due to lack of fuel due to the injectors not opening. If it will crank but won't start pull the plugs to see if they're wet or not. Make sure it's gas not water (check it with a match), put heet in the gas tank.

Moving on to no spark. Read clarks. Check DME relay (or just put your spare in). Could be DME - bad solder joints. Could send it in to have it resoldered. Or the DME could be bad. Could still be the ignition switch - there must be a way to test this. Or, if it's old it wouldn't hurt to put a new one in.

Doesn't sound like AFM to me but it couldn't hurt to look inside - both at the barn door & at the swipe deal. Also clean the connector to the AFM with contact cleaner.

Just thinking out loud to try and help - I know that you've already done most of the stuff on this list. What about the speed and ref sensors & connectors? Cap & rotor? Plug wires? Coil wire? Noid light?

hermesbooking · 10-13-2008, 03:35 PM

For fuel pressure, I am running about 38-40 on start-up and 34 druing running. I purchased a kit from lyndsey racing that has the adapter to put a fuel gaue at the end of the fuel rail.
DME Relay, I have 2 of the newer P/N, both seam to be good, one is brand new.
AFM. Took it apart almost a year ago and cleaned the contacts inside like everyone suggested. Seamed to be good. I am leaning toward the speed and position sensors now. I did check them with a multi-meter, but have been told by an experanced mechanic, that was is not 100% accurate, so I am leaning toward those. Not 100% sure, but trying to get everything appart to make sure I ahve the 80 mm gap needed on the wheel.

924Sman · 10-13-2008, 04:02 PM

8mm not 80! weeeeee

hermesbooking · 10-15-2008, 03:57 PM

Sorry about that, I did mean 0.80 mm. Thanks

ihuntsum · 10-31-2008, 01:25 PM

Any updates. What do you mean by .80 mm at the wheel?

hermesbooking · 11-07-2008, 03:50 PM

Wanted to give an update. Got the 2 sensors in today installed them. The speed and ref sensors. Both measured good. the .80 mm and still have a no start issue. Any more sugestions? I am lost and just spent 200 bucks on some sensors to have the sam problem. Thanks Mike

ihuntsum · 11-20-2008, 11:08 AM

Well my spare tire, jack, and tool kit arrived today and the ole Porsche became my daily driver. Went to have a new exhaust installed to celebrate and the doggone thing killed on me and I had to get it towed home AGAIN. Last time I cleaned the reference sensor connections and cleaned up some wire splicing issues with one of them and it started running fine again. Today after towing - NO SPARK.

I think hermesbooking and I share a similiar frustration. I have worked on planes a little in the past in exchange for flying time. Helper only, no A&P credentials. I was also a diesel-electric locomotive mechanic for 15 years. I don't pull wrenches on the trains anymore but I still supervise a couple of the mechanics and frequently have to oversee other mechanic work that is farmed out and one thing that burns my butt up is parts changers. Early in my mechanical career I was taught how to break down a system and troubleshoot a faulty component to the point where when it was replaced I knew it was bad. Now, true to form, I had a few instances where multiple faults occurred simoultaneously but I could always feel good that at the end of the day, a replaced part was in fact bad. I was fortunate to have a large inventory of spare parts and sometimes I just changed suspect components in an effort to save time but if this did not solve the problem immediately I would re-install the old part and dive into the troubleshooting.

The problems I have with the Porsche is that I do not have good reference information other the folks in this forum and neither do I have an inventory of spare parts. As stated above, I hate to just change parts and prefer eliminating non-faulty components thru qualification rather than hit and misss replacement.

OK - so how about some suggestions relative to troubleshooting the no-spark out of the coil issue. I would prefer a systematic approach and since I have no spark out of the coil, maybe some information such as voltage or current readings that should be supplying the coil, etc.

For what it is worth, I used to prefer breaking down an electrical schematic (which I do not have for this 85.5 Porsche 944 NA) into halves. ex- I have no spark out of the coil but I do have a solid 12v at the battery. If an electrical component (say an ignition switch - has 12v out of it in the start position) then everything between the battery and ignition switch is eliminated.