Very Frustrated

[ursmkd]

How good is your fuel pump? Had similar issues and it turned out to be a dying fuel pump

[dkahler]

I have checked the fuel pressure at the rail and I got around 39psi. How did you know your pump was starting fail?

[rick13]

Well I put new injectors in...didn't fix my flutter. New plugs and wires...still fluttering. New O2 sensor...no help.

I am down to bad AFM, bad wastegate, bad fuel lines, ???

I just don't understand why when it gets heated up over a few miles...it runs fine???

[minho78]

Originally Posted by rick13

Well I put new injectors in...didn't fix my flutter. New plugs and wires...still fluttering. New O2 sensor...no help.

I am down to bad AFM, bad wastegate, bad fuel lines, ???

I just don't understand why when it gets heated up over a few miles...it runs fine???

Rick please explain the no boost. If you mean you press the gas and it buckles then I would suggest the TPS. If the car runs fine and no boost and latter you have boost then it,s the Cv. I installed a new one 4 years ago and the other day it was acting up. It was cutting a 6 psi and latter it was letting the car overboost. I see a MBC in the future.

[minho78]

Originally Posted by dkahler

Hello Everyone,

I have posted before but not for a while. I have a 86’ 951. I love the car and have it almost exactly the way I want it. It is almost set up stock. The purpose of the car is to be a track car. The car is experiencing two issues.

The first issue is that the car seems to be running very rich. I park the car in the same place and it has left a very prominent black spray of exhaust on the floor about 2 feet long. This is what is leading me to believe that the car is running rich.

The second issue is when WOT in 3rd gear around 5000rpm or 4th at around 5000rpm the car will seem like it retards the timing, resulting in a drastic loss of power. Stepping on the accelerator results in bucking and stuttering. If given minimal gas to maintain speed, after about 8 - 10 seconds power is restored. A few times after this experience, the car will die at a stop. It will instantly start back up and drive normally. I have tested with boost limited between 5 psi - 15psi and the issue happens regardless of the boost level.

Both of these issues have been occurring for over 6 months now. I have read every thread I could find on how to resolve these issues. Here is a list of what I have replaced and tested in the vehicle.

New Universal O2 sensor (Car does NOT have a catalytic converter)
DME Temp sensor (Tested against Clarks garage specs) tested OK.
AFM (Tested against Clarks garage specs) tested OK.
New TPS sensor
New Spark Plugs changed in “July 12”
New Spark plug wires
New Distributor
New Rotor
New Coil
New Knock Sensor
New Engine Mounts
New Fuel Pressure Regulator 2.5
New Speed sensor
New Reference sensor
New (Remanufactured) DME with a stock chip
New (Remanufactured) KLR with a stock chip
New Timing belts
New (Remanufactured) Idle stability valve
New Fuel filter
New vacuum hoses
I have bypassed Cycle Valve
Added Manual Boost Controller
Stock wastegate (Tested against Clarks garage specs) OK
Added aftermarket boost gauge

I have installed the LED blink code tester and there are never any codes.

I feel that I have tried everything listed on the Internet to resolve the issues. Any help or insight that you might have would be greatly appreciated. I am literally out of ideas and very frustrated.

Thanks

Ok if you have no cat the soot is normal. Now the power loss it could be two things overboost or car running lean and klr retards time. It shouldn't shut off. I see you have an aftermarket boost gauge which is good but you should add a Wide band o2 sensor to see if the car goes lean at that rpm. GLuck

[dkahler]

<!-- BEGIN TEMPLATE: bbcode_quote -->
<div class="pre-quote">
Quote de <strong>dkahler</strong>
</div>

<div class="post-quote">
<div style="font-style:italic">Hello Everyone,<br>
<br>
I have posted before but not for a while. I have a 86’ 951. I love the car and have it almost exactly the way I want it. It is almost set up stock. The purpose of the car is to be a track car. The car is experiencing two issues. <br>
<br>
The first issue is that the car seems to be running very rich. I park the car in the same place and it has left a very prominent black spray of exhaust on the floor about 2 feet long. This is what is leading me to believe that the car is running rich.<br>
<br>
The second issue is when WOT in 3rd gear around 5000rpm or 4th at around 5000rpm the car will seem like it retards the timing, resulting in a drastic loss of power. Stepping on the accelerator results in bucking and stuttering. If given minimal gas to maintain speed, after about 8 - 10 seconds power is restored. A few times after this experience, the car will die at a stop. It will instantly start back up and drive normally. I have tested with boost limited between 5 psi - 15psi and the issue happens regardless of the boost level. <br>
<br>
Both of these issues have been occurring for over 6 months now. I have read every thread I could find on how to resolve these issues. Here is a list of what I have replaced and tested in the vehicle.<br>
<br>
New Universal O2 sensor (Car does NOT have a catalytic converter)<br>
DME Temp sensor (Tested against Clarks garage specs) tested OK.<br>
AFM (Tested against Clarks garage specs) tested OK.<br>
New TPS sensor<br>
New Spark Plugs changed in “July 12”<br>
New Spark plug wires<br>
New Distributor<br>
New Rotor<br>
New Coil<br>
New Knock Sensor<br>
New Engine Mounts<br>
New Fuel Pressure Regulator 2.5<br>
New Speed sensor<br>
New Reference sensor<br>
New (Remanufactured) DME with a stock chip<br>
New (Remanufactured) KLR with a stock chip<br>
New Timing belts<br>
New (Remanufactured) Idle stability valve<br>
New Fuel filter<br>
New vacuum hoses<br>
I have bypassed Cycle Valve<br>
Added Manual Boost Controller<br>
Stock wastegate (Tested against Clarks garage specs) OK<br>
Added aftermarket boost gauge<br>
<br>
I have installed the LED blink code tester and there are never any codes.<br>
<br>
I feel that I have tried everything listed on the Internet to resolve the issues. Any help or insight that you might have would be greatly appreciated. I am literally out of ideas and very frustrated.<br>
<br>
Thanks</div>
</div>
<!-- END TEMPLATE: bbcode_quote -->Ok if you have no cat the soot is normal. Now the power loss it could be two things overboost or car running lean and klr retards time. It shouldn't shut off. I see you have an aftermarket boost gauge which is good but you should add a Wide band o2 sensor to see if the car goes lean at that rpm. GLuck

Thanks for the post. If I am running lean what would I do to correct that?

Thanks DK

[dkahler]

**Update**

Well, I have done a few more things to address the issue. I sent my injectors to Witchhunter and one came back bad. I have replaced the bad one with a refurb injector. I also have replaced the original AFM with a refurb one. In addition, I identified a hole in my exhaust manifold. I have also replaced that with a good used manifold. I have also shimmed my wastegate.

Unfortunately, the issue still persists. Things that I have noticed: I installed a fuel pressure gauge on the rail. When idling the pressure is around 32psi. When I manually rev the engine from the throttle body, the pressure fluctuates up to 40psi with the higher revs. I don't know if that is normal or not.

The issue is very consistent. Right around 5000rpm in 3rd gear, it feels like the timing is retarded causing the car to drop horsepower. I don't think that it is an overboost issue as my aftermarket boost gauge shows a max of 12 - 13psi. In addition, once the issue happens, if I lift off the gas and then apply gas, the car bucks and sputters. Once I come to a stop, the car dies and needs to be restarted. Once restarted it drives fine again.

At this point, I almost have replaced everything in the car. The only things that I have not replaced are the fuel pump, fuel dampner and BOV.

My thought is perhaps chipping the car might fix the issue. Can anyone explain what happens when a fuel pump starts going? Does anyone think the BOV might make a difference?

I really appreciate any input. I have to be close to addressing the issue, as I almost have a brand new car.

thanks Doug

[dkahler]

Well, I finally solved the issue. I replaced the Afm with a refurb, no help. I then replaced the fuel pump with a new Bosch unit, no help. Finally, I went with aftermarket chips for the DME and KLR and that finally fixed the fuel / timing retard issue.

Now the car is running amazingly great. Thanks again to everyone who contributed thoughts and suggestions.

[rick13]

Nice! And congrats. That's gotta feel good.

Not so for me. I will finish replacing all vacuum lines, venturi lines, idle stablizer and its lines, knock sensor, J-boot...anything that wasn't replaced two years ago during rebuild...is NOW! I have already replaced fuel pump, injectors, and chips.

Minho,
It feels more like a "miss", therefore... by nature, is fails to produce boost. Again, the weird thing is, it runs fine after it reaches high operating temps. The reason I say "high" is because I need to be running at operating temp for like 5 miles at 60+ mph, then, and only then will the car drive 100 %.

My thermovalve was leaking vacuum badly as well. I am replacing that too. I will also replace my rotor and dist. Cap.

I will button her up this weekend and report back. Wish me luck

P.S. I already replaced my TPS

[Ky914Newbie]

Originally Posted by dkahler

Well, I finally solved the issue. I replaced the Afm with a refurb, no help. I then replaced the fuel pump with a new Bosch unit, no help. Finally, I went with aftermarket chips for the DME and KLR and that finally fixed the fuel / timing retard issue.

Now the car is running amazingly great. Thanks again to everyone who contributed thoughts and suggestions.

What is different on the aftermarket chips? Was it hitting overboost which has been removed by using the aftermarket chips? There may still be a problem that you haven't identified. If it is hitting overboost for a mechanical issue, you may be taking a big risk.

[dkahler]

I don't think the car was suffering from over boost. The reason I think that is through my manual boost controller I have the boost limited to 12psi. So I am not worried about blowing the head gasket. I have replaced everything else in regards to the fuel system. With the aftermarket chip it does remove the protection of the stock chip but also remaps the fuel delivery. After 8 months of trying to resolve the issue, I guess I am willing to take some risks.

[rick13]

Well I completely rebuilt intake/all new vacuum lines J-boot, dist. cap, rotor etc. Still flutters...so it was down to the wastegate. Or was it...

I installed new lindsey dual port waste gate and ... Still flutters.

She idles better, my boost (when all warmed up) is more steady and over all, she runs better.

I did notice in playing with my boost, that at 3/4 throttle there was NO FLUTTER !!! I just replaced the TPS a couple of months ago (trying to figure this out then too), so I have a hard time believing that it is bad. I will call Lindsey and ask if there is a chance I got a remanufactured TPS...

No way, right???

The only thing I haven't replaced is my AFM, and my fuel lines.

Anyway "still frustrated"

[dkahler]

Have you had your injectors checked? When I sent mine off to Witchhunter one was bad. I did notice a change in the cars performance with four good injectors. Again, for me the only thing that eliminated the issue was an aftermarket chip set. I would highly recommend a manual boost controller and a boost gauge to ensure nothing negative happens to your engine.

[rick13]

I just installed 55# injectors with Lindsey Chips. It has gotta be my AFM!!! I've replaced damn near everything else.

I will be replacing it in a couple weeks...of course, I will report back.

[ERAU944]

Rick, what 55# injectors are they?

New or used?

Injectors are not all created equal...

[rraulston]

wow I'm going through all of this now. My vacuum lines were so bad I had to remove the intake manifold just to get to them. I'm still in the line change phase. I broke that valve that controls boost (dunno the name) the nipples were SOOO brittle. The MBC is half the cost of replacing it. I just don't know what to do with the vacuum lines going to it???

[rick13]

UPDATE: I switched out my DME and KLR and everything is perfect.

[Roger 911]

I'm resurrecting this thread because I bought the 951 previously owned by the OP, dkahler (Doug). Kind of a funny story, but Doug lives down the street from me and we are now in frequent contact, in a good way! This is extremely helpful, being able to ask him what he did when, why, etc. having said that, neither he nor I have been able to resolve the intermittent power cut out at high revs. If you go back through this thread, you'll see that Doug has replaced or tested virtually everything that is commonly referenced as having any potential to impact this issue. I just recently replaced the coil as well.

To recap, here is what I am currently experiencing.

- If you were to drive this car like my wife, you would never know there was a problem.
- If you give it full throttle and let the revs climb past 5K, that's when the problems can occur. Sometimes you get a little hesitation as the revs climb into the 5-6K range, other time it will completely shut off at 6K.
- It appears to be related to the boost pressure. When I cranked the boost down to 5 psi, it seemed to stop.
- I set the regulator now to achieve around 11 psi of boost.
- I noticed sometimes it seems to achieve this boost level, but other times it does not. I understand that 4th gear is probably the best gear to test this in. Unfortunately, there is no where other than a racetrack to safely test this at 6K in 4th gear.
- If I put it in 4th and give it max throttle, it seems to hold the boost steady up to close to 5K (as high as I have gone).
- If I give it max throttle and let it rev in lower gears, sometimes (not always) I've noticed that the boost goes up, then actually begins to decrease as the revs rise. Falling from 10 down to 6 psi by 6K. This seems odd to me.
- The other thing that is going on, and may or may not be related, is the AFR changes. Sometimes at idle, it reads full lean, then other times it stays full rich. Then others it bounces back and forth. When it goes rich, the idle also increases by approx 200 rpm. The O2 sensor is relatively new. Similary, the AFR will sometimes read rich under part or closed throttle. Then other times it will change from rich under part throttle to lean at closed throttle (more of what I would expect).

About the only thing left to replace is the turbo itself. I certainly appreciate any thoughts.

Thanks.
Roger

[rick13]

Hmmmm...."completely shut off" ! ... that's electrical. Falling from 10 psi to 6 psi can be indicative of a weak or failing waste gate.

[Roger 911]

Originally Posted by rick13

Hmmmm...."completely shut off" ! ... that's electrical. Falling from 10 psi to 6 psi can be indicative of a weak or failing waste gate.

Yes, the shut off seems like over boost protection, except that supposedly, the 951 MAX chip does not utilize this. The drop in pressue would certainly imply wastegate. However, both of these seem to conflict.

Roger