86 assistance please! (idle problem) (with movie and a couple pics)
#16
Captain Obvious
Super User
Super User
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Get a can of starter fluid and spray around the top of the engine (except the intake tubes). If the rpms increase, you have a vacum leak. This is an easy way of finding vacum leaks.
#18
Nordschleife Master
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Well I disconnected the MAF and the car isnt puffing any black smoke, so it is very possible that the maf is out of spec,
I also checked the fuel pressure, and with engine off and pump bridged I am getting just under 40 PSI which is roughly 2.7 bar, which is the highest according to the factory manual, I then started it and recieved about 31PSI of pressure which is 2.1 bar, the manual says approx 2.0 bar, so this would actually cause it to lean out abit if I am not mistaken,
now the car is still not idling correctly it still pulsates and doesnt rev up at all.
I am pulling about 15.2-15.2 in hg of vacuum at the same time, and when it "drops off" I can hear an electronic ticking in the engine bay, I am not sure what that is but I am guessing the injectors,
I am going to pull and clean the plugs as due to running it so rich they may have some junk on them, and I will recheck the wire order, however I at abit of a loss as to what to do other than that as I tried disconnecting the TPS to see if that made a difference and it didnt.
I am abit stumped atm as I should still be able to rev up the car with 15 in hg of vacuum even if it was a leak, it shouldnt throw it off THAT much but I could be wrong
I also checked the fuel pressure, and with engine off and pump bridged I am getting just under 40 PSI which is roughly 2.7 bar, which is the highest according to the factory manual, I then started it and recieved about 31PSI of pressure which is 2.1 bar, the manual says approx 2.0 bar, so this would actually cause it to lean out abit if I am not mistaken,
now the car is still not idling correctly it still pulsates and doesnt rev up at all.
I am pulling about 15.2-15.2 in hg of vacuum at the same time, and when it "drops off" I can hear an electronic ticking in the engine bay, I am not sure what that is but I am guessing the injectors,
I am going to pull and clean the plugs as due to running it so rich they may have some junk on them, and I will recheck the wire order, however I at abit of a loss as to what to do other than that as I tried disconnecting the TPS to see if that made a difference and it didnt.
I am abit stumped atm as I should still be able to rev up the car with 15 in hg of vacuum even if it was a leak, it shouldnt throw it off THAT much but I could be wrong
#19
Nordschleife Master
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
seeing as how I am notorious for skipping basics, I decided to check the plugs and well, I think I found my issue,
my spark plugs were all loose
and of course due to running rich covered, I am just going to install new plugs and this time tighten them to speck, and pray that is the issue
and I found that if I disconnected the MAF and the O2 that there was black smoke, but just MAF no smoke, but still smelt rich,
I find it suprising that the engine still ran/idled (somewhat) with plugs this loose, as they were barely hand tight, didnt even need a ratchet on 1!
my spark plugs were all loose
![ooops](https://rennlist.com/forums/graemlins/icon501.gif)
and I found that if I disconnected the MAF and the O2 that there was black smoke, but just MAF no smoke, but still smelt rich,
I find it suprising that the engine still ran/idled (somewhat) with plugs this loose, as they were barely hand tight, didnt even need a ratchet on 1!
#21
Nordschleife Master
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
well I have installed new plugs, and torqued to spec, and still exactly the same issue,
at this time I have also tested a MAF that was good about 6 months ago, or resonable anyways,
I have tested my brains in a 85 and they are fine,
I am still pulling 15in HG of vacuum, sharkmeister thinks that this "could be" due to the fact that it isnt idling that fast,
I am having a friend bring over a timing light with electronic tach so we can see what it is actually revving at.
is it possible that the pickup sensor is bad?
or how about a broken wire, and if a broken wire, where do I start looking/testing.
or should I assume that the intake didnt seal properly when I took it off and had it powdercoated, and attemp to reseal it.
at this time I have also tested a MAF that was good about 6 months ago, or resonable anyways,
I have tested my brains in a 85 and they are fine,
I am still pulling 15in HG of vacuum, sharkmeister thinks that this "could be" due to the fact that it isnt idling that fast,
I am having a friend bring over a timing light with electronic tach so we can see what it is actually revving at.
is it possible that the pickup sensor is bad?
or how about a broken wire, and if a broken wire, where do I start looking/testing.
or should I assume that the intake didnt seal properly when I took it off and had it powdercoated, and attemp to reseal it.
#22
928 Collector
Rennlist Member
Rennlist Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Colin can you check each brain wire for wiring faults? I would continue on the path you're on, ie replacing parts till it works ... but I'd say you should consider that the hall sensor may be inop (passenger cam front) or that there's a wiring fault. Check for blown fuses .... also check the basics. Yes timing light is a great idea. Make sure the dealies that amplify the EZF signal are OK (the "final stages") ..... and then, look at fuel delivery (though it seems like ignition issues.
#24
Nordschleife Master
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
I am not aware of a hall sensor I will look into that on the manuals see what it says,
I doubt I have a leaky injector but it is very possible, but that wouldnt explain the not being able to rev up issue,
as per the final stages, if they were defective I wouldnt get spark would I?
and I have spark at all holes, and when i pull the spark lead off each hole the engine does make a change
I doubt I have a leaky injector but it is very possible, but that wouldnt explain the not being able to rev up issue,
as per the final stages, if they were defective I wouldnt get spark would I?
and I have spark at all holes, and when i pull the spark lead off each hole the engine does make a change
#25
Nordschleife Master
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Heinrich, I just checked Pirtle's site and searched the board, but I dont see anything like the hall sensor on the 86 engine, do the 85/86 cars have this?
#26
Nordschleife Master
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
ok pictures are worth 100 words
here is a movie of the car running, http://www.geocities.com/cjensan928s...S/mvi_2441.avi when it idles somewhat normal it is pulling about 12.5in HG of vacuum, but you can watch the vacuum bounce around,
also I just want to verify that this is the Temp II sensor![](http://www.geocities.com/cjensan928s/928/TS/img_2440.jpg)
and that this is for the AC (has been deleted)![](http://www.geocities.com/cjensan928s/928/TS/img_2438.jpg)
but I am not sure what this wire is for
it is right by the jumper post and the 14 pin connector.
I am at this time baffled, is it at all possible to get the harnesses on the wrong bank? I didnt think it would be due to the placement of the Temp II sensor and the airbox sensor.
here is a movie of the car running, http://www.geocities.com/cjensan928s...S/mvi_2441.avi when it idles somewhat normal it is pulling about 12.5in HG of vacuum, but you can watch the vacuum bounce around,
also I just want to verify that this is the Temp II sensor
![](http://www.geocities.com/cjensan928s/928/TS/img_2440.jpg)
and that this is for the AC (has been deleted)
![](http://www.geocities.com/cjensan928s/928/TS/img_2438.jpg)
but I am not sure what this wire is for
![](http://www.geocities.com/cjensan928s/928/TS/img_2437.jpg)
I am at this time baffled, is it at all possible to get the harnesses on the wrong bank? I didnt think it would be due to the placement of the Temp II sensor and the airbox sensor.
#27
Three Wheelin'
Join Date: Dec 2003
Location: Vancouver, Canada
Posts: 1,729
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
So I'm thinking of anything. What about vacuum to the tranny? Is that hooked up? How about checking into your throttle linkage? You had to rig a new one when you deleted the mech fan. Can it be backwards? I'm really grasping at straws here. You know it will be something silly!
Glenn
Glenn
![Confused](https://rennlist.com/forums/images/smilies/confused.gif)
#28
Nordschleife Master
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Hey Glenn,
I tested the vacuum going to the tranny, and it was going into the actuator (or whatever the name is) and leaking right out, I even replaced the rubber O-ring in it, no help, so I dont have that connected until I pull that piece out of the tranny,
I know for a fact that the throttle linkage is pulling the right way, and I verified that the TPS is registering that the trottle is indeed closing,
I know it will be probably something silly,
but the only thing I can think of atm is that seeing as how I am getting only 12.5 in HG of vac while it is idling HALF normal is that the intake didnt seal 100% to the head when I reinstalled it, I tried using brake cleaner but it didnt seam to affect the running unless I sprayed it right into the intake, although I am going to try to use some water to try to trace it tomorrow, and we will see if I can find a leak that way, of course the water will be in small doces, VERY small doces,
I tested the vacuum going to the tranny, and it was going into the actuator (or whatever the name is) and leaking right out, I even replaced the rubber O-ring in it, no help, so I dont have that connected until I pull that piece out of the tranny,
I know for a fact that the throttle linkage is pulling the right way, and I verified that the TPS is registering that the trottle is indeed closing,
I know it will be probably something silly,
but the only thing I can think of atm is that seeing as how I am getting only 12.5 in HG of vac while it is idling HALF normal is that the intake didnt seal 100% to the head when I reinstalled it, I tried using brake cleaner but it didnt seam to affect the running unless I sprayed it right into the intake, although I am going to try to use some water to try to trace it tomorrow, and we will see if I can find a leak that way, of course the water will be in small doces, VERY small doces,
#29
Nordschleife Master
Thread Starter
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
1 question is what prevents using a S4 intake gasket on an 85/86 engine if the S4 intake manifold will bolt up to it after you cut off 1 bolt? or can you.
#30
Sharkaholic
Lifetime Rennlist
Member
Lifetime Rennlist
Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
You can but there is more to it than one bolt. I would rather go the other way, keep the 86 intake and add S4 heads.
Final stages are the doo dads mounted in front of the radiator, but I don't think this is your problem.
Check the idle control valve and the idle adjustment screw on the throttle body. If you close the idle adjustment screw on the throttle body all the way it should die at idle without any go pedal. If it keeps running then you have unmetered air getting into the engine from some where. Make sure all the boots for the intake runners are good and tight. I have had eratic idle before from unmetered air getting past these boots.
Final stages are the doo dads mounted in front of the radiator, but I don't think this is your problem.
Check the idle control valve and the idle adjustment screw on the throttle body. If you close the idle adjustment screw on the throttle body all the way it should die at idle without any go pedal. If it keeps running then you have unmetered air getting into the engine from some where. Make sure all the boots for the intake runners are good and tight. I have had eratic idle before from unmetered air getting past these boots.