ebbowron

Good morning all,

So, Ill start by stating that prior to my upgrades yesterday, this was a problem. Simply put, yesterday, I installed Lindsay Racing basic RWHP upgrade kit, including the boost enhancer hose, 3.0 BAR fuel pressure regulator, and the KLR and DME chips, into my 1986 951 (BTW, I am a complete novice mechanically and technically, and these upgrades were really easy with Lindsay's instructions). I love the drive and feels smoother but similar to when I had Autorthority chips in it years and years ago, before I went back to stock for the last 25 years.

Both before and after I upgraded my car, wrhen I accelerate quickly (pedal to the floor), the car runs great up to about 4k RPM. From 4-6 RPM however, the engine fails to continue to accelerate smoothly, and kind of stumbles/skips unless I back of and slowly build up. This hasnt always been the case, but I couldn't tell you when the problem began because I drive the car pretty gently (been with my pops and I for almost 30 years). Just troubleshooting with all of you, as I know many of you have vastly more mechanical and technical knowledge that I do. Trying to determine if this is something that will require a trip to the shop. or something simple I could check on myself.

Thanks in advance for any assistance all. Happy Sunday driving!

931guru

Sounds like a weak fuel pump. Hook up a fuel pressure gauge and have a passenger monitor the gauge while you try to duplicate the symptom. If the pressure falls too much, you will get stumbling and backfiring.

greggm5

I would also check all the charge air connections. I had a similar issue. Would release air and then draw the hoses back in under vacume

ebbowron

I’ll look into the fuel pump and the charge hoses! Thank you!

Frank@Work

You also might want to check the coil.

Dan Martinic

Spark plugs

The Bosch ones are not lasting very long these days

ebbowron

So an update on this and any recommendations would be appreciated. I havent had much time to self-diagnose the issue.

I dont think its the fuel pump because if you back of the throttle and gradually work into it, it will get to high RPM. Also, just a note, I did put in Lindsay Racing Wastegate just prior to doing all this, so there is a new wastegate in the vehicle.

I noted last night that it was fine in 1st gear, but 2nd, 3rd, and 4th, it would stumble, and kind of "gasp" at about 4k RPM until I backed off and let it gradually build up. Even in 4th it seemed to have a hard time to build up.

I am not sure where the "charge air connections" are too be honest. I did put a Lindsay racing boost enhancer in, and checked all those connections and all seemed good.

I am considering purchasing the Lindsay Racing "Tune Up" kit with some NGK BR 7EIX plugs, new iginition lines, distributor, and MSD Blaster Coil. I have a master spreadsheet that has all my maintenance done, and I cant even find the last time the spark plugs have been done. Do you all think this is a worthy upgrade for $300? Or, should I just track down some NGK 7EIX plugs and start with that? I kind of figured if I was going to do it, might as well do it all now vs. peace meal it.

Thanks again for any advise/assistance. If I do the plugs/wires/cap/coil and it doesnt work, Ill probably bring it in to be diagnosed. Just trying to do what I can do first.

THANKS!!

ebbowron

By the way Frank I have followed your 951 build for like 2 years it seems. It's absolutely amazing.

mj951

Take the booster out and see if that changes things.

ebbowron

Thats a great idea mj951. I want to say I had a little bit of this problem before I put everything in, but that the problem seems more pronounced. It will only take five minutes to return to stock so Im going to give that a go...

ebbowron

If it does in fact change things, what would be the solution to properly installing it?

mj951

Lindsey's site shows an installed picture, you should be able to understand it from there.
Make sure it's oriented in the right direction. They have a link to additional information but info is missing.

Another thing to verify is your fuel pressure. Good write-up on Clark's Garage for that.
http://www.clarks-garage.com/

ebbowron

I did an oil and filter change yesterday, and took the booster out. With the booster out, everything ran great. So, to narrow this down, I did install it as shown on Lindsay's site, however, the original silicone "short hose" (I dont know what the name of that hose is), was too short for the boost enhancer to sit flush, so I had to go to a local auto store and get a longer one, HOWEVER, that one is just straight rubber, not silicone. Could that be the difference? I needed about an extra 1/2" the original hose obviously did not provide, which makes me think I was doing something wrong. Also, when installed "correctly", that boost enhancer is rubbing my roof liner. I plan to replace the roof liner in the coming months with a rubber one like the ones below, but wondering if I then don't have it installed properly?. I may try to re-install and take photos to post in the thread if necessary so that you can see how I have, or "had" it installed.

Thanks again for everyone's help

Dan Martinic

The boost enhancer is a simple ball & spring pressure regulator; it blocks flow until a certain psi then it opens. You can take a bike pump and see what that psi is (I'm guessing around 7-10).. and confirm what direction the air flows.

If removing it solved your problem, I wonder if your issue happens right when it opens. Do you have the stock cycling valve (boost control)?

Is your new wastegate single port or dual?

The hose should not matter as long as connections are air tight

ebbowron

this was the configuration here. It seems maybe it’s just opening the flap on the wastegate maybe? Air flows r-l…