re. i87 5kt intermittent no start

[Dave Yentema]

re. i87 5kt intermittent no startBen, 

Here is some more details on the car, sorry about the length. I'm just hoping that someone will be able to see something that i'm missing. almost ten years of working on cars hasn't been able to help me much on this project.


I have been working on this car for over a year now. It was a friends car for about a year(throughout which being is i'm pretty mechanically inclined and trained i was it's main mechanic) and then my friend gave it to me this past november. Its previous owners NEVER did any real maintnence on it, and when i got it i decided to give it a complete overhaul(well as complete as a college student can afford)  First thing i did was a near complete tune up. The cap was pretty new, so i just cleaned it up and i have yet to find a correct rotor. Every one i find is made for a smaller diameter shaft than what I have. All of the vacuum lines were solid, and i ended up getting the wrong spark plugs because i didn't know better(bosch platinum dual electrode plugs). I took it through inspection and it passed with flying colors. Drove it around as a pleasure car for a few months, and a whole bunch of things went wrong at once it seems. My car started throwing codes for a bad knock sensor and a faulty/mis aligned hall sender. Shortly thereafter, i blew the idle screw out of my car. (someone has obviously tampered with the CO mix and the screw at some point before). I shoved a plastic plug in the hole and the car started and ran beautifully. 

When it came time for the next oil change, I ran a can of seafoam through the gas tank and into the hole in the IM where the srew is supposed to be. After that is when my car started acting like it had a clogged fuel filter, hesitated on accelaration and the frequency valve was buzzing at irradic intervals. I figured that i had just sucked up some of the coating in the gas tank. it wasn't too bad yet, and my MPG weren't too knocked out of wack so i let it go for about a month. During this month I met up with someone i met through AW and we spent a good day working on the car. We replaced the knock sensor, found that one of the hall sender wires had rubbed through and was grounding out, and discovered that my idle switch was out of adjustment (it wasn't clicking into idle mode when it should've been). I tested the switch for WOT and idle modes, and it worked fine once adjusted properly. This guy gave me a spare idle screw that he had and we adjusted the idle with it to a little below 800 where it should be and I left to go home. I stopped to get some gas and the screwball at the gas station gave me regular instead of high test like i had asked for. After this was when my fuel filter was REALLY clogged(bad tank of gas). And while on the way home, i blew out the idle screw again ( bad o-ring). Shoved the plug back in there and left it like that for a long time. Changed the fuel filter which illiminated the hesitations that i was having as well as the irradic buzzing for about a month. Changed the filter yet again and the hesitations went away, but the buzzing did not. It was shortly after this that i noticed it was slightly harder to start it cold than it used to be (had to crank it a little extra, and once it started it would give me this BLEH BLEH BLEH BLEH almost like it was missing until i rev'd it a few times) And intermittently while it was running, mostly on deaccelaration and occasionally at a stop light it would start running like this as well. While it would run like that, the frequency valve would start buzzing very loudly until the idle leveled out. I soon got my 3in exhaust installed, and went to go through inspection. I failed because my CO was .06% too high (standard is .5, i was at .56) Fast forward to today. I finally got a new idle screw to put in, put it in till the o-ring grabbed, started the car and it started and ran perfectly. It was idling a little high so i turned the screw in some to lower it to where it should be and all was well, no more frequency valve buzz or pulsing idle or anything. Shut the car off and went to start it again and all it did was crank. Backed the screw out some, the car fired once but it didn't catch. Checked for codes and got none. Backed the screw out some more and cranked it and it fired once again, but still didn't catch. And it wouldn't fire again until i turned the ignition off and back on again. Disconnected the ISV and blew into it while it was on, and it was open. When it was unplugged it was sealed. (Sorry if i got those two mixed up, either way it was working as it should) Sprayed some cleaner into it and put it back together. tried starting again, same story. Took my screw out and put my plastic plug back in. Same story. Put a piece of tape over the hole with a very tiny hole in it, car starts right up. the frequency valve was buzzing irradically again though. Unplugged the ISV while it was running and the RPM slowed way down to the point that it died. Put the screw back in and turned it in ALL the way, to the point that it was opening the butterfly valve a good ways. Started the car, and it was running at about 1300RPM. Backed the screw out till the Idle switch clicked and then about a turn further. Car was running great, right where it should be idling. I put a piece of tape over the screw as a pit of cheap insurance that i don't lose yet another one and took it out for a test drive. Drove great, no hesitation or rough idle or anything. Boosted great, etc. Shut the car off and started it up again to see if it was still gonna run, and run it did. 

Let it sit for about 30-45 min and went back out to start it and it fired once and didn't catch (sound familiar?...) tried it again and right as it fired i punched the gas pedal and it roared into life. When I let off the gas pedal it would rumble down it it's usual rough idle before stalling out unless I held it at around 2k for a minute or two then when i would let off and it would sound like it was missing (same usual rough idle it was having) before leveling out at a good speed. Still no frequency valve buzz or anything of that sort. Drove out and picked up my new NGK plugs, put them in, went to start and boom same story. Got it started and took it for a ride and it had a lot more pick up than with the bosch dual electrode things. 

Again, sorry about the length but i feel that everything in there may provide a clue as to how i can solve this problem...

thanks,
Dave



  ----- Original Message ----- 
  From: Ben Swann 
  To: yentemad at rider.edu ; quattro at audifans.com 
  Cc: 'Ben Swann' 
  Sent: Tuesday, May 13, 2008 8:58 PM
  Subject: re. i87 5kt intermittent no start


  How did you check the throttle body switch?  Did you actually verify operation - that the switch makes and breaks contact by using a test connector?  Did you verify there are no broken wires off the switch?  Did you run connectivity test from the ECU connector through the switch?


  More:  what happens when you disconnect the ISV connector - does the idle drop?

  What happens when you pinch the air line into the ISV - does this alter the idle?

  I have found in general, the idle switch adjust is about 3 full turns out  (MC-1/MAC-11) to produce proper idle.  This is when CO is adjusted properly and no - I repeat NO airleaks.  YMMV.


  You provide a lot of info here, but no complete description of the problem.  If you just got the car, assume a lot of sorting is in order and you will find leaks.  OK - get back on that to see if this leads to a proper diagnosis.


  Ben



  [Date: Tue, 13 May 2008 19:17:37 -0400

  From: Dave Yentema <yentemad at rider.edu>

  Subject: i87 5kt intermittent no start

  To: quattro at audifans.com

  Message-ID: <000e01c8b54f$8873e680$fb6e4b0a at DEATH>

  Content-Type: text/plain;       charset="iso-8859-1"

  Figures that when i finally get all of the right parts installed, my car doesn't want to run right. I took that plastic plug out that i had filling the hole for the idle screw, and installed the right one. Screwed it in until i heard the throttle switch click, then backed it off by about a half a turn. Car starts right up and runs like a champ, a little too high rpm, but was running very well. Shut it off, played with a few things like the isv, the throttle switch, etc and went to start the car again. It fired once but didn't catch and then didnt fire again until i turned the key off and back on again but still didn't catch. Went back out and played with some more things, took the MM hose off, cleaned the gunk off of the butterfly valve, backed the screw off a bit, etc. Tried it again, no luck. Tried one more time, but this time i punched the gas right as it fired and it caught and i held it at about 1500 for a bit and let off. It stumbled around for a bit but eventually started  idling beautifully. On a quick test drive it ran amazing as well. Shut it off and went to start again, and its doing it again... I used this as an excuse to get some new spark plugs (NGK bp6et)and it runs a lot smoother, but still has this problem..

  Any ideas?



  -Dave]