Surging/surges/bucks ..

[SNK-BIT]

Thanks for all the help guys. I am assuming it's dynotune time if I want to fix this. I appreciate all the help and good luck with yours. I'm going to call this thread dead.

P.S. Not to be a pest, but what is the verdict on the throttle body? Keep it or send it back and go for the 70mm? Thanks.

 

[bat-stang]

My heads are the stock GT40's with a valve job, Bullet 77maf and 65mm throttlebody. My computer is a non-cobra specific '92 processor. Talking to (the now defunct) owner of South Houston Motorsports (the builder of my car), his response to the A9L is that the difference is a slight change in the ignition curve, and something else (can't remember, sorry)--very minor differences, in his opinion. Very persuaded, in his experience, that the A9L doesn't cure this particular problem. I only have the bucking on cracked throttle, but non existent during vigorous driving, and only at 1700 rpm. It's more like a slight stumble than a full on buck--unless I begin to pull from that rpm, then it clears pretty quickly. I think that #2771 hit it with the lean condition/timing curve. It's really a non issue with me--if something IS actually wrong of course I'm concerned; however, if this is notorious, it's part of the package. This car has been built with a bit higher rpm range in mind, and I do notice a slight loss of torque down low compared to my bolt on 88 Gt, but it's made up for in mid range to top end performance. Would I rather better low end response? Maybe in certain situations, but for me this is actually a small price to pay for a real 290-300 hp at the wheels. My ride comes alive (noticeably) at about 3300 rpm--I mean almost like a carb car after its throat has been cleared--and runs like a scalded dog to its 6800 rpm redline.

With my tune I was warned against the 70--let alone the 75 throttlebody. My car is mild compared to yours though: was told that my off the line would suffer.

 

[93Cobra#2771]

FYI - bullet meters aren't the most accurate meter, they are around the accuracy of the C&L's. You can try clocking it and see if that helps (clear KAM each time you clock it, and then drive it for 20-30 miles if various conditions)...

 

[bat-stang]

FYI - bullet meters aren't the most accurate meter, they are around the accuracy of the C&L's. You can try clocking it and see if that helps (clear KAM each time you clock it, and then drive it for 20-30 miles if various conditions)...

I haven't had any issues with Bullets in either of my cars; who would be the most accurate of the aftermarket meters?

 

[93Cobra#2771]

PMAS are generally considered the most accurate.

 

[bat-stang]

PMAS are generally considered the most accurate.

I thought that PMAS and Pro-M were one and the same:shrug:

 

[93Cobra#2771]

They are/were. The bullet meters were a low cost (not as accurate) meter made to compete with the not as accurate C&L's pricewise...

 

[bat-stang]

Wow--now I really feel good about my $200 purchase!:cryying:

 

[bat-stang]

Actually I had a C&L on the car when I first bought it--Way off--but the Pro-M has been good for me.

 

[SNK-BIT]

Hummmm..thread still open..ok then, here goes..from where I left off..After "talking" to yall I pulled my plugs for a look see and they are snow white. I pulled the vacuum from the fuel pressure regulator and set it at 50psi. I also disconnected the 02 sensors, reset EEC and went for a drive. I can definitely say it was a step in the right direction as the "bucking" was mostly gone. I brought it back in, pulled the plugs and they actually had color to them. Put the same plugs back in, pulled the spout connector and set base timing to 8 degrees (from 13) and reinstalled spout. Went for another drive and it was the best it's been since I have installed the new parts. Pulled the plugs again and they look decent. Motor really felt sluggish as expected.

93Cobra#2771, this seems to back up the theory about a lean condition and timing. Will the EEC adaptive still take over with the vacuum off the FPR and the 02's being disconnected? Do I need LEE93COBRA's old MAF and 42lb injectors for the mods I have? If it is down to a MAF and injector's, what do you guy's suggest. I'm think the most would be an 80MAF set for 30lb injectors for what I have then have it tuned.

LEE93COBRA, I don't mean to push but, how soon will it be before you tear into your motor? I really want to hear the outcome of at least the recal before I plop down the cash for something I don't need. That sounds mean huh. Better you than me or some crap. Naw, it's just I want to DRIVE my car! As stated above the fuel and timing has done more for this problem than any of the other parts I have changed! I'm just hoping.

bat-stang, thanks for the heads up on the throttle body. I returned it for the 70mm. I would like to keep all the bottom end torque I have now but more power upstairs won't hurt if the motor is putting out what I (optimistic) want/think it should be. I read that a 95 GT 5 speed computer will work with stock Cobra motors. Fact or fiction? I would like the capability to be able to do the (DCL) real time read of all sensors. I know, I know, but a "real" computer cost so much!

Thanks again for all the help.

 

[LEE93COBRA]

Not sure. I hope to so during the month of August but I/we have a customer engine build and install to do, rebuild a tranny for another, do a gear install for another, and intake, timing chain, header install for another. So my month may be a little to busy to work on my car

 

[SNK-BIT]

FYI - bullet meters aren't the most accurate meter, they are around the accuracy of the C&L's. You can try clocking it and see if that helps (clear KAM each time you clock it, and then drive it for 20-30 miles if various conditions)...

I thought the computer was adaptive? If so..to me..this meant no matter what part was changed, ie.. clocking the MAF, that the computer would eventually adapt to the new part. I did not realize it had to be "cleared" after every parts change under it's control but it makes sense. Once again I find myself learning something new. So that means I've made a lot of part changes with "skewed" results and should do it over?

LEE93COBRA it seems I'm in the same situation with making time for the changes. Glad :beer: you have so much business. At best, it will probably be the end of Sep before I can do the tune. I'll keep yall posted.Thanks

 

[bat-stang]

The computer is adaptive, but if the sensor its looking at is off, the rest of the baseline will be off as well. I had my car leaned out during some dyno time (the fuel pressure reg. was adjusted to compensate). Guess what the computer did? It adjusted the fuel pulse of the injectors to compensate for my un-cycled adjustment... For my adjustment to hold, the computer had to identify my new adjustment as baseline.

 

[SNK-BIT]

Well I changed a few parts and made it to the dyno yesterday for some numbers but no tune yet. I received the wrong power pipe so I'll be waiting on the tune but was curious about the additions.

The bucking is still there and so is the craptacular idle.

To add insult to injury, I only made 273 to the wheels. 30rwhp? I'm depressed! I've added AFR 165 heads, Comp 270HR cam, 70mm throttle body, AFM Power Pipe, 30LB injectors, and an PMAS 80mm MAF calibrated for the pipe, injectors, and stock X3Z computer. It was running fat (10/11s) but do the numbers sound right? I feel with the correct pipe,fuel and tune I should be closer to 300rwhp. Is this about right or am I expecting too much? Don't get me wrong the car hauls when on the floorboard but, I don't tend to drive it that way constantly.

If the power pipe, etc does not put things in order I'm ready to reinstall the stock cam to at least lose the bucking and bad idle as it seems to be where that problem lies.

Is anyone here using a AFM power pipe on their Cobra? The pipe I got was the AF-0112C and no way will it fit my Cobra. It looks like I should have the AF-0105C pipe instead?

Thanks.

 

[LEE93COBRA]

the a/f is killing your numbers. Get it up to mid 13 a/f and you should see around 300rwhp.

What's wrong with the power pipe? Do you mean that it will not fit through the hole in the inner fender? If so, I am sure that is true since you ordered the 4" pipe. It will require modification to the inner fender.

 

[99SVT3753]

99s did it lot as well .. and being speed limit on base (military) I'd have to downshit and run a lil higher rpm or else feel like the clutch and rearend would be shot out the bottom of the car

 

[SNK-BIT]

the a/f is killing your numbers. Get it up to mid 13 a/f and you should see around 300rwhp.

What's wrong with the power pipe? Do you mean that it will not fit through the hole in the inner fender? If so, I am sure that is true since you ordered the 4" pipe. It will require modification to the inner fender.

Thanks Lee..I knew the a/f was really hurting the #'s. As it wasn't a tune, I had 3 pulls and used the last 2 for pulling some (5psi total) fuel out. It's the only adjustment (F/P/R) that I have. That’s how I made the 270rwhp. I do hope to get the correct pipe to improve airflow and less fuel. Then go for the “tune”.

Your right about the power pipe needing a 4" hole to be made in the existing 3" hole next to the shock tower. I knew this when I decided to purchase it. I wanted the "cold air kit" . When I talked to the AFM tech I told him I had the 70mm throttle body and a PMAS 80mm "shorty" MAF. He said no problem, that is what we recommend and it would fit everything I had. The problem is the pipe is longer than the length from the throttle body to hole by about 2-3 inches. In other words if I connect the pipe up to lets say the throttle body the other end goes "past" the 3" hole! It lands somewhere between the 3" and the stock airbox hole.

The other thing is, even if that could be worked out, I do not have the room for a coupler between the throttle body and the pipe as the pipe touches the throttle body and won't drop down past the shock tower but lays on top of it. It seems this would be made for an LX or GT but not the Cobra intake as the throttle body inlet sticks out farther on the Cobra intake. If the Cobra throttle body inlet was shorter then it would let the pipe move toward the engine and be able to drop between the engine and the shock tower.

The last problem is the coupler will not fit my 70mm throttle body. They install a reducer in the 4" elbow but no way would it squeeze down to my throttle body opening.

Links to power pipe with pictures..http://www.andersonfordmotorsport.com/

I'll call Tuesday to straighten it out, but am afraid my PMAS is set for the 4" pipe, not a 3.5 (which I think is the correct one) if that makes a difference. That means trying to convince PMAS to recal my meter for free and i'm thinking good luck with that.

Oh well,crap happens.

 

[racerbox77]

Im not getting a bucking at all with my set up BUT Im getting a CEL..
(stock motor from throttle to pan. 80 mm ProM, SQ trim, power pipe, 11psi., 30lbs. inj., 39psi at idle-52lbs. press. at full boost, full length headers, x-pipe no cats, flowmaster cat back, A9L.)
CEL comes on after about 10 minutes of driving only when I let off the gas. If it comes on and I give it a little gas right away it will go back off until I let off to come to a stop or just to coast.
This just started after I installed the ProM, 30lb inj., power pipe, and A9L. The ProM has the holes all around instead of the sample tube like C+Ls. Clocking MY mass air would be pointless with a ProM because it has the holes all around instead of the sample tube right? Im thinking the O2s are going out of their range when I let off and the unburned gas from the bigger injectors passes through. If thats true then maybe a dyno tune would fix this. The car runs very strong and drivability isnt affected by the light. Any suggestions would be awesome

 

[SNK-BIT]

Im not getting a bucking at all with my set up BUT Im getting a CEL..
(stock motor from throttle to pan. 80 mm ProM, SQ trim, power pipe, 11psi., 30lbs. inj., 39psi at idle-52lbs. press. at full boost, full length headers, x-pipe no cats, flowmaster cat back, A9L.)
CEL comes on after about 10 minutes of driving only when I let off the gas. If it comes on and I give it a little gas right away it will go back off until I let off to come to a stop or just to coast.
This just started after I installed the ProM, 30lb inj., power pipe, and A9L. The ProM has the holes all around instead of the sample tube like C+Ls. Clocking MY mass air would be pointless with a ProM because it has the holes all around instead of the sample tube right? Im thinking the O2s are going out of their range when I let off and the unburned gas from the bigger injectors passes through. If thats true then maybe a dyno tune would fix this. The car runs very strong and drivability isnt affected by the light. Any suggestions would be awesome

I'll trade your CEL for one that bucks/surges/hitching:rollseyes . I do not know much about power adders but there are alot of folks here that do. Do you or can you have the car scanned for any codes now that you have the A9L? I'm really interested on this as i've asked about converting over and did not receive an answer. After I change a part and reset computer, it seems about your time frame (10 min) or about 15-20 miles of driving it starts it's bucking again. I assume it's the computer "adaptive" taking over? I assume you reset the computer after all the parts were changed? Was the ProM calibrated to the A9L, Pipe and 30lb'ers? I have tried clocking the MAF but it seems to do no good for me but it could be worth a try. Do you have an "original" ProM" or is it the newer PMAS like mine? The reason I ask is mine has just a sample tube at the 12 o'clock position. It might be a moot point to try and clock it then. Good luck and let us know.

 

[93Cobra#2771]

They make the PP longer to fit ALL intakes, I had to trim about 1" off mine on the throttle body side to fit my car.

You are leaving HP on the table with the rich a/f and the stock X3Z timing tables, no doubt.

I have the 3.5" PP, and I had to squeeze the coupler down to fit my stock throttle body as well. There are companies out there that make couplers with reducer ends if you get desparate. I went with the 3.5" simply so I didn't have to make the hole any bigger.