RDS928S

Gents,

Is there a way to lean out the engine with the AA chip set simply by adjusting the air/fuel mixture screw?.

RDS

jeff jackson

RDS...my car is an 86.5 model with auto trans, the Original MAF, and stock exhaust...and it has been running the AA chipset, with Bosch Platinum+4 plugs for several months now, absolutely no indication of "running rich" as of yet. I've pulled the plugs twice since installing the chips, and have been satisfied that the A/F ratio is at least as satisfactory as the stock chipset was, and I'm noticebly up on power and torque over the stockers. The "mixture" adjustment,on US model 85-86 cars, is a "plugged" screw in the MAF housing...preset at the factory, and requiring no end user adjustment. So...if the LH is unable to correct the mixture sufficiently to prevent a overly "rich" idle condition, you might need to seek out John Speake for having him "recalibrate" your MAF. I'd definitely change out your O2 sensor first (it controls the mixture, at all conditions except Idle...and WOT)...and during spirited acceleration, or WOT...I'd prefer things abit on the rich side, as compared to leaner. As for Idle...how much are you idling the car anyway ?

MarkRobinson

you want to run about 28.5psi @ idle with 19-20" vacuum, this seems to be the "average" for AA chip tuning on an '85-86 car with exhaust.

On all 3 of my '85-86 cars, saw 25-35rwhp MINIMUM to the wheels Kibort: no news here. 250rwhp stock-ish, 275/285-ish after. My 2nd 86.5 car went from 253 to 302rw/296tq with these mods.

Mark.

RDS928S

Jeff,
my early 86S idles smoothly with the tach needle slightly below the last hash mark before the 1000 rpm hash mark.
Some times when cold the idle drops below that setting and the engine hunts & stumbles very badly-never stalls though.
Already ordered a new 02 sensor. When I get it installed will post results.

Rich.

John Speake

On the 85-86 US cars, even if you remove the blanking on the idle mixture adjust pot, it will only adjust the mixture at idle. It has very little affect above idle.

It appears that the AA chips suit the US 85-86 pretty well, in general.

But their S4/GT chips appear to often result in too rich running over the range, also suffer from pinking.

jeff jackson

The cold idle issue, could be several issues, first of which, air leaks. The Rubber hoses that connect the intake side plenums to the individual runners, are notorious for cracking and leakiing. Also, the hose that runs from the Idle Air Control motor, to the throttle body, Check the O rings where the MAF unit attaches to the throttle body. False air...will cause this problem. Lastly...if you have a Mity Vac...use Wally Plumleys excellent write up on checking the vacuum system for leaks. My guess is...you do these things and your drivebility will improve greatly.

Shane

Shane Elliott '86.5 5sp Chips & RMB = 281rwhp 278rwtq My car was stock otherwise.

Ed MD

Mark is correct about optimal fuel pressure with the AA chip set. I have dyno results- stock, and with exhaust and chip/afr. The AA chips are rich, if you follow the advice when you install the afr and increase the fuel pressure to 34-36, you will be tooo rich. The factory settings should be at 30. My experince mirrored Marks, and I eventually tuned down to 28.5. Stock HP was 249 at the rear wheels, after tuning with afr/ exhaust mods, AA chip and tune-up ( fresh plugs, and plug wires, new O2 sensors etc.) the best run was 292 at the rear wheels at 28.5. ( at 30/ "factory" it was 284). In hindsight, I would recommend leaving the stock regulator but do the rest. This will save you about $350 between the cost of the afr and the dyno time. Ed

Shane

Cool thanks for the tip Ed!
So by what you have learned for an extra $350 I can get appx. 10rwhp more with a rrfpr?

Shane

You all realize something? With those simple mods an '85-'86 can be putting down the same numbers as a stock (healthy) running GT!!

Not only that but our cars weigh in less than a GT! Double bonus!!

TopDownL79

Glad I listened when several people said that the 85-86 cars were the best bang for the buck!

AA and "X" here I come!

mark kibort

so, for what ever reason, the 85s have been kept down, making them the sleeper find of the 928s! key is that they have the best cams available of any 928, but have the smaller valves and slightly lower compression.
you dont see too many euro 85s putting down 290ish to the wheels! with using the S4 heads, it would be up .5 point or so with compression and probably rival the GT as far as the best 5 liter out there! I think the 85s still use the dual disc clutch, right?

hey, with a by pass tube the holbert car was running about 290rwhp , before the tune up, vented air box, screen removed, fuel reg turned up, etc.

by the way, are you guys still running screens in the maf??? remove them both and let me know what you got. while your in there, vent the air box too!

bet you are all looking at 300+hp at the rears!

torque peak at around 4400rpm, hp peak at 6200rpm, like mine with flappy kept open?



mk

Ed MD

My numbers are with screen, closed airbox and hi-flow cat ( Cobb county mandates cats, even with random inspections roadside usually because of a loud exhaust!). I vacillate whether to tuned to max HP possible versus keeping in the form that I run on the street. Looking to get DR's intakes for the 85.
Also I sent the chips back to AA to have them remap them to try to eliminate a flat spot in the A/F curves that occur at 2500-3500 rpm ( see Mark Robinson's pre-turbo posts). Once I get them back, I'll dyno and post the results to see if anyone else is interested in sending their chips back to AA.
Ed

Imo000

Mark,

Yes the '85s, the '86s and even the Euro S2s have a dual clutch. All changed to the single disk system when the S4s body came out in late '86.

mark kibort

what are you waiting for!!!! get those screens out of there. TONs of losses through even one screen, let alone 2. you have a filter, what could possibly enter the intake MAF?? unless you drop something in it when you are working on it. its a saftey screen, not a screen used to filter anything, thats the real filter's job. put it this way, when screens were mounted to the jump jet Harrier, it couldnt take off! (safety so no-one or nothing would get sucked in to the compressors) just a screen!

probalby why im getting such high numbers . no screens and a vented air box(and good fuel air numbers)
MK