PorscheHusky

Hi everyone! New here and while I hate to make my first post something unfortunate..

My 84 is having some weird problem and it started last year in October 2010.
I woke up went to work, everything was perfectly fine. The car sat for about 3-4hrs then I went to drive out and have lunch else where. Well suddenly no start, just cranked itself silly till it ate the battery.

Time lapse; it sat there at my work for about 2 days before she suddenly decide to fire up, however she struggled badly to stay alive and I had to flutter the throttle just right to make her live and warm up. Meanwhile, smoke is storming everywhere out of the back; literally a cloud of it but as she got warmer, the smoke faded and stopped then she purr at a steady 900rpm.

I got her home safely and killed the engine immediately as not to do any possible further damage and began my tests.
Just so it is known, I have done the following to the engine prior to this sudden problem;
~New injectors
~new filters
~new pressure damper and regulators
~Oil change


Things done after the problems shown up (hoping to fix it);
~New DME/Pump relay
~had AFM tested
~Ohm tested my Speed and Ref senors
~New fuel Pump (it soon died during the course of winter)
~new DME temp sensor
~Compression and leakdown test: Cylinders (passed)
~Cooling system pressure and leakdown test (passed)


I got a little discouraged and left her untouched for a long time after I could not figure out what was the problem. After a while she would just start then immediately die or not even sputter at all which was really furstrating. I could not even THINK about touching the throttle or it would sputter and die. Not to mention it was still throwing smoke like a mad RAM 3500 Heavy Duty.

Just recently, as of a few months ago, I got irritated and just started pulling plugs and cranking just for kicks and to my surprise, as soon as I pulled the plug to the DME Temp Sensor, she fired up and idled a strong 900-ish rpm and I could rev it without it dieing!
She still threw some smoke but nothing compared to when this problem first show up, just little puffs and the occasional 'gust' of smoke when revved. But the moment I plug the Temp Sensor back on, it bogs and wants to die or becomes very brittle as if there were a vac leak. The first use of the throttle would kill it unless fluttered just right.
I have videos of this if any one is daring enough to wrap their mind around this

I want to blam the DME for this; I am 90% positive it is the DME but I feel like I could be missing something, maybe you guys can help me figure out all the possibilities I may have over looked.

joonas

You could test TPS (Throttle Position Switch). You can test DME temp sensor also.

Use Clark's site http://www.clarks-garage.com/shop-ma...ure-index3.htm

FPR could be also the problem.
http://www.clarks-garage.com/shop-manual/fuel-07.htm

John_AZ

In a recent thread that the owner did many things you have done and more-replaced the DME--it came down to a loose rotor screw.

Solution posted on post 17.
http://forums.pelicanparts.com/porsc...ml#post6129787

The DME temp sensor could have bad/shorted wire. Check the pins on the big DME 35pin connector to make sure the wires are secure and the pins straight and not corroded. Could also be an internal solder joint.

I suggest you go back to the basics and check all the grounds-expecially the one hiding under the dash above the fuse/relay block, clean the top engine electrical connections, check the wires, plugs, use a NOID lite, wiggle the DME computer connection and tap the DME box while cranking. Check the reference sensor wires and connection for torn sheiding and shorting.

Unplug the O2 sensor and see it it helps---unpluged causes a "rich" fuel at idle.

If you think it could be the DME---maybe try the resolder tips

GL
John

86-951

I recently spent several weeks working through a no start problem. I did have a bad DME but after replacing it, wound up in the same situation you describe. I had checked the speed and reference sensors while troubleshooting the original DME problem and they checked OK (using just a resistance measurement) so I ignored them. I eventually checked them again while the car was in the no start state and found the reference sensor bad. Replaced it and the start issue along with a bad misfire when the engine warmed up are gone. I would check them again especially when the car won't start.

PorscheHusky

Is there a skematic that shows which pin(s) are for the temp sensor so I can accurately check it(them)? I have the DME off and opened the back side of it and even the frontside and all the solders look fully intact and ok however the board has some concerning discoloration in a certain part of it (will have pictures when I get home, at work as I type this). Other than that everything 'visually' to the best of my knowledge looks ok.

I'm just abit paniced at the moment cause so many symptoms are happening with no real direct lead. I will check the things you stated above and recheck them 2 more times to reach a verdict then update you on what is going on.


When you say the "Same situation" Do you mean everything exactly? Smoke too? When I saw the smoke that bad and continually smoking it gave me a really bad scare (Thinking my head gasket bit the dust). I hope that is not the case, can not afford taking appart my engine to that degree just yet Plus my cooling system gets super pressurized and is spitting coolant (occasionally) when I let the engine ilde for more than 10min.

I too have heard that the TPS could contribute to the problem but would it really cause it to throw smoke like that???

PorscheHusky

Here is one of the videos I made a while ago of this situation. It is fairly recent, of course after I figured out how to 'pacify' the problem

The smoke is hard to see but it is there at an idle, just little puffs.
The tests conducted in this vid was souly to show exactly what is going on with the plug off then on, then what happens when I flutter the throttle in both scenarios along with the 'noticable' volume of smoke it is throwing.

As I do more tests I will try to video document them so you guys can see exactly what I am experiencing, plus Video evidence is always best, ja?

John_AZ

The attachment is close. Pins 14 & 15 control our 4 injectors. FYI the injectors fire all at once-4 together, twice per cycle.

Use cheap Bosch copper plugs or similiar.
Again, check the injectors with a NOID lite.

Have you ever cleaned the injectors?

Have you figured out why the new fuel pump died? Was there a short from the DME fuel pump relay? Could this wiring be bad?

Check this wiring circuit carefully. Do you have the electrical schematics?

GL
John

PorscheHusky

My injectors are all new. I got rid of the old ones after the system supposedly got clogged, which in turn is what killed my pump, I suspect.
My fuelcell was loaded with crud from the walls of the steel cell and I cleaned out as much as I could then topped it off with fresh fuel after an initial rinsing. I literally redid the entire fuel system (hence the new injectors) just for my safe knowledge in knowing that 'shouldn't' get faults any time soon. All of this was done in November of 2010.

Also, the pump I have on it now is still functional and new; the original, from the factory, one is the one that bit the dust. When I tested to see if the pump was seeing power; I tied my meter to the leads and cranked and it was getting a solid 11.4V (I have the pictures somewhere as proof). But as a saftey, I still purchased a second DME relay 'just in case' never know when the backup may be in handy

And thanks for the schematics! I will study that tonight and see what I can come up with. one thing that is on my mind though, the injectors corresponding to the DME sensor, are they direct or is there a medium inbetween their communication? I may not have worded that question properly but what I am getting at is; Does one control one-another directly?

John_AZ

If I understand your question , the speed sensor signal will tell the DME how often to pulse the injectors and trigger the coil. That is why if you have a "no start" you always check to see if the tach bounces 1/16th of an inch to signal the DME.

Have you reset/gapped the reference/speed sensor recently? Per Clarks

GL
John

PorscheHusky

I have yet to check them again from the last time I checked and set them (March 2011)

I get tach bounce plenty and like I say; when I have the temp plug off, the engine fires up on the 1 or 2nd crank sometimes, literally.

But if those evil sensors are the medium, then I shall priobably just check them before mnightfall; their connections anyway. I do have a bad feeling the connections may not be tip top condition.

As for grounds. The vast majority of wires, grounds included; on the car will be replaced soon. I cleaned them all up but just recently (and after looking at some restoration threads here) I got a huge motivational boost to get it done and get it done correct!

PorscheHusky

In these two pictures; shows a sectoin of my DME's board (the top side board; the side facing up when installed on the vehicle).

See the area around that red chip? Is that normal or is that a bad sign? What is under that chips control or what does that chip do?
There is even a smige (or looks like it anyway) on the texas instruments chip, the one dead center closest to the red chip.

John_AZ

Sorry, I do not know the answers.

I can only direct you to the "solder" links and maybe the info is there.
https://rennlist.com/forums/924-931-...ferrerid=20449

Or

https://rennlist.com/forums/924-931-...referrerid=204

GL
John

joonas

Fuel air mixture is not right that is why engine does not run like it should.
It could cause smoking. First get the mixture right then deal with smoke.

When you changed the injectors did you get the correct ones? If new injectors have different flow rate you cannot get the engine running ok with stock chip.

PorscheHusky

Got them from Pelican Parts; so I trust they are the proper ones :P as most of the parts bought; from Pelican.
Is there any sure way to test for a faulty TPS?

StoogeMoe

Well, first of all, that isn't the DME temperature sensor that you are pulling in your video. That is the coolant temperature sensor for the gauge. Sounds like you need to replace that, as it may be shorted internally, causing your voltage to drop when plugged in.

As far as the smoke, it looks to me like it is on deceleration, which would indicate worn rings. This looks like a totally unrelated issue to your running problem.