928 Proud new owner
10-03-2010, 02:08 AM
#46
Three Wheelin'
Join Date: Jun 2008
Location: Surprise, Arizona
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It's absolutely gorgeous... A fuel pressure gauge installed on the fuel rail is a great weapon on these cars. They're cheap and explain alot during diagnostics. Roger's got em', and I believe Mark carries them too. I'd go through and clean all of the grounds. Then verify fuel pressure. At least you have other cars tp allow swaps to check for function. Why are you thinking electronics?
10-03-2010, 02:53 AM
#48
Rennlist Member
Charley,
Your link did not work... its wants me to log into your AOL account. can you try resending in another format?
Also what wheels are you running on the GTS? Have any pics you can email me Waynes@email.com. I'd like to modernize my look and need to see what looks good and how they fit etc. thanks.
Your link did not work... its wants me to log into your AOL account. can you try resending in another format?
Also what wheels are you running on the GTS? Have any pics you can email me Waynes@email.com. I'd like to modernize my look and need to see what looks good and how they fit etc. thanks.
My GTS wheels are 18" after market turbo twists. Front 8" and rear 11" I think.
By the way there is a thread on here somewhere with nothing but wheels to give you lots of optional ideas.
10-03-2010, 03:26 AM
#49
Nordschleife Master
Ok, sounds like ignition is firing both banks, and your MAF is at least passably good.
Next few things I'd check (one at a time) would be:
1. Disconnect the battery, then re-connect a couple of mins later.
The LH stores adaption parameters for MAF age, and idle speed, based on O2 sensor and EZ-K inputs - its not unheard of for these to end up corrupt. After reconnecting the battery, it'll re-learn the adaption (takes around 10 mins of driving, during which expect the idle to hunt a bit).
2. Measure fuel pressure.
This should be done with engine off and pump relay jumpered, and also at idle. Then also watch for how long the fuel rails hold pressure after the pump is off. The workshop manual has the specs for pressures and leakdown time.
These will tell you whether the pumps are up to scratch, and whether the injectors are blocked and failing to close properly. As an aside, did you replace the fuel filter? (sitting since 2005 would likely cause varnish issues)
3. Disconnect the O2 sensor
The lead comes through the side of the tunnel in the passenger footwell - it has a 3-pin round Sureseal connector. Possible the O2 sensor is bad and causing mixture issues.
Next few things I'd check (one at a time) would be:
1. Disconnect the battery, then re-connect a couple of mins later.
The LH stores adaption parameters for MAF age, and idle speed, based on O2 sensor and EZ-K inputs - its not unheard of for these to end up corrupt. After reconnecting the battery, it'll re-learn the adaption (takes around 10 mins of driving, during which expect the idle to hunt a bit).
2. Measure fuel pressure.
This should be done with engine off and pump relay jumpered, and also at idle. Then also watch for how long the fuel rails hold pressure after the pump is off. The workshop manual has the specs for pressures and leakdown time.
These will tell you whether the pumps are up to scratch, and whether the injectors are blocked and failing to close properly. As an aside, did you replace the fuel filter? (sitting since 2005 would likely cause varnish issues)
3. Disconnect the O2 sensor
The lead comes through the side of the tunnel in the passenger footwell - it has a 3-pin round Sureseal connector. Possible the O2 sensor is bad and causing mixture issues.
OK Hilton... so I unplugged MAF. Ran the car. It runs worse with MAF unplugged. Not only was the car stalling out to the 300-400 rpm range, with the MAF unplugged the motor went hunting for rpms till it finally flamed out. So worse....
Being that the car stalled out no matter what temp... I wouldn't think the sending unit had any relation, but I checked it any way against resistance as you suggested. Both temp II posts had very similar resistance against ground. So..... still hunting for ideas.
A couple of clues that may help:
1) motor ran "fine" when we picked it up and drove home after purchase, and didn’t pick up this stalling attitude till the 3rd day, and I was half way across the desert on my way to UTAH. It was a very hot day, with AC on car temp was approaching 195. So I pulled off freeway to fill up and let her take a rest. On the off ramp, after about 6 hours of near perfect performance.... it died on the off ramp and been happening ever since. As I pull up to a stop light etc, it dies about half the time, other half rpms hang on long enough to stay alive.
2) I do seem to notice the slightest engine miss... being that I have no real point of reference, I am assuming the motor should have zero vibrational miss. I come from a BBC in my past life, (you can see my home page link for pics of the last car I build) and I’m use to large cams, but this...it’s definitely a miss across the entire RPMs. I planned on taking it down to Dave Lummis place in SLC to have him "feel" the pulse and see if I’m just being too sensitive etc.
So not sure if this has anything to do with the diagnosis, but usually all symptoms sometimes can turn on a light bulb... any feedback from all helpers is appreciated.
If not I guess I have to pull off the manifold to R&R ISV? I hate to pull manifold until my mistress and I get to know each other better first... I mean was only have 1,000 miles together and it may be a bit too soon to be rounding second base together.
Oh and here is a new pic today and I gave her a bath and a fresh wax.
Wayne
Being that the car stalled out no matter what temp... I wouldn't think the sending unit had any relation, but I checked it any way against resistance as you suggested. Both temp II posts had very similar resistance against ground. So..... still hunting for ideas.
A couple of clues that may help:
1) motor ran "fine" when we picked it up and drove home after purchase, and didn’t pick up this stalling attitude till the 3rd day, and I was half way across the desert on my way to UTAH. It was a very hot day, with AC on car temp was approaching 195. So I pulled off freeway to fill up and let her take a rest. On the off ramp, after about 6 hours of near perfect performance.... it died on the off ramp and been happening ever since. As I pull up to a stop light etc, it dies about half the time, other half rpms hang on long enough to stay alive.
2) I do seem to notice the slightest engine miss... being that I have no real point of reference, I am assuming the motor should have zero vibrational miss. I come from a BBC in my past life, (you can see my home page link for pics of the last car I build) and I’m use to large cams, but this...it’s definitely a miss across the entire RPMs. I planned on taking it down to Dave Lummis place in SLC to have him "feel" the pulse and see if I’m just being too sensitive etc.
So not sure if this has anything to do with the diagnosis, but usually all symptoms sometimes can turn on a light bulb... any feedback from all helpers is appreciated.
If not I guess I have to pull off the manifold to R&R ISV? I hate to pull manifold until my mistress and I get to know each other better first... I mean was only have 1,000 miles together and it may be a bit too soon to be rounding second base together.
Oh and here is a new pic today and I gave her a bath and a fresh wax.
Wayne
10-03-2010, 04:08 PM
#50
Instructor
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Join Date: Sep 2010
Location: Alpine, UT
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OK....so here is what happened.
1) I unplugged battery ground for about 15 minutes. Drove, same problems for about first 5 miles. I decided to really "get on" the car this point. ran through gears to near rev limit. On ,y 2nd or 3rd time doing this, at about 5,500 rpms the tach started jumping from 5.500 to 6,500. (as if there was a short in the tach). It did this in 2,3 anf 4th.
So i pulled over all the more confused...scratching my head... and low and behold the car didnt stall and was now idelling at 1000 rpms and now idels perfectly.
Hmmm....
so sounds like there is a short and me "getting on it' some how reconnected the short and alls back to where is was.
Or.. resetting the computers was the tricks and the tach jumping was normal in this process.
1) I unplugged battery ground for about 15 minutes. Drove, same problems for about first 5 miles. I decided to really "get on" the car this point. ran through gears to near rev limit. On ,y 2nd or 3rd time doing this, at about 5,500 rpms the tach started jumping from 5.500 to 6,500. (as if there was a short in the tach). It did this in 2,3 anf 4th.
So i pulled over all the more confused...scratching my head... and low and behold the car didnt stall and was now idelling at 1000 rpms and now idels perfectly.
Hmmm....
so sounds like there is a short and me "getting on it' some how reconnected the short and alls back to where is was.
Or.. resetting the computers was the tricks and the tach jumping was normal in this process.
10-03-2010, 04:53 PM
#51
Nordschleife Master
1000 rpm idle is too high - you've got a vacuum leak somewhere. Spray some brake cleaner around the intake while running and see if revs change.
I'm guessing its one of the breather hoses (front passenger side usually cracks first).
I'm guessing its one of the breather hoses (front passenger side usually cracks first).
OK....so here is what happened.
1) I unplugged battery ground for about 15 minutes. Drove, same problems for about first 5 miles. I decided to really "get on" the car this point. ran through gears to near rev limit. On ,y 2nd or 3rd time doing this, at about 5,500 rpms the tach started jumping from 5.500 to 6,500. (as if there was a short in the tach). It did this in 2,3 anf 4th.
So i pulled over all the more confused...scratching my head... and low and behold the car didnt stall and was now idelling at 1000 rpms and now idels perfectly.
Hmmm....
so sounds like there is a short and me "getting on it' some how reconnected the short and alls back to where is was.
Or.. resetting the computers was the tricks and the tach jumping was normal in this process.
1) I unplugged battery ground for about 15 minutes. Drove, same problems for about first 5 miles. I decided to really "get on" the car this point. ran through gears to near rev limit. On ,y 2nd or 3rd time doing this, at about 5,500 rpms the tach started jumping from 5.500 to 6,500. (as if there was a short in the tach). It did this in 2,3 anf 4th.
So i pulled over all the more confused...scratching my head... and low and behold the car didnt stall and was now idelling at 1000 rpms and now idels perfectly.
Hmmm....
so sounds like there is a short and me "getting on it' some how reconnected the short and alls back to where is was.
Or.. resetting the computers was the tricks and the tach jumping was normal in this process.
10-03-2010, 05:31 PM
#52
Rennlist Member
Pretty much all these cars need through ground point cleaning and vac hose review.
When I start there, the rest is easier.
Intermittent running can be caused by both.
When I start there, the rest is easier.
Intermittent running can be caused by both.
Last edited by Landseer; 10-08-2010 at 12:02 AM.
10-07-2010, 11:09 PM
#53
Drifting
[QUOTE=auzivision;7940405]
A while back I picked up a set of workshop manulas for $200… great investment, but I think this set is way overpriced. Just keep an eye out for a set of these:
QUOTE]
Just FYI... These appear to be reasonably priced:
http://cgi.ebay.com/ebaymotors/Deale...item2eb0548331
A while back I picked up a set of workshop manulas for $200… great investment, but I think this set is way overpriced. Just keep an eye out for a set of these:
QUOTE]
Just FYI... These appear to be reasonably priced:
http://cgi.ebay.com/ebaymotors/Deale...item2eb0548331
