North American Turbocoupe Organization



Did a dyno pull... found some problems.
moneypit Offline
Member
#1
Let's start with the good news:
181 RWHP
270 RWTQ

The bad news:
It's off-the-chart lean. Even with the Walbro 255lph High Pressure fuel pump. At 15 PSI boost it stays lean all the way accross- at 8 PSI it starts out stoich but instanly goes waaaaaaay lean when the turbo spools up.

I've got an adjustable FPR on the way and I'm going to take out the injectors and check them out, also I'm putting a muffler back on it since I think that the lack of backpressure and speedy exhast scavenging is screwing with the O2 sensor. Gonna mess with the VAM a bit, too- trick it into dumping some more fuel. Gonna buy me an AF guage while I'm at it...

But, the neat thing is- this definitely proves the durability of this engine! I've been beating the hell out of it with too much boost and barely any fuel for quite a while now! Yeah... I'm a retard.
'88 TurboCoupe, '01 Impala, '83 Crown Vic, '95 Jeep Cherokee, 63.5 Galaxie Fastback, '57 Studebaker President... So many cars, so little time.
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Huey866 Offline
Posting Freak
#2
There is no such thing as lack of backpressure on a turbo car. Some people are running just downpipes and doing fine with them. I even ran with just a down pipe for a couple of months.
87 TurboCoupe - silver, 137k, 5-speed, 3.73 w/ superior axles, Maximum Motorsports suspension, 03 Cobra Brakes, 93 GT vacuum assist, Griggs Subframe connectors, RR cam, Essy Adj. Cam Gear, Boblog, Bob Elbow, .63 T-3, ARP headstuds, Stinger 3in Exhaust, Magnaflow Muffler, AEM gauges, Tweecer RT, Godspeed Omega 18x9
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moneypit Offline
Member
#3
Quote:Originally posted by Huey866:
There is no such thing as lack of backpressure on a turbo car. Some people are running just downpipes and doing fine with them. I even ran with just a down pipe for a couple of months.
That's what I always thought, but I'm thinking it may have something to do with my lean condition. Either way it's obnoxious!
'88 TurboCoupe, '01 Impala, '83 Crown Vic, '95 Jeep Cherokee, 63.5 Galaxie Fastback, '57 Studebaker President... So many cars, so little time.
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Joe F Offline
Posting Freak
#4
Off the chart lean? Do you have the dyno chart? A graphical representation of the pull would be very helpful in the diagnosis.
JR's Place - My '87 Turbocoupe
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Half-Pint Offline
Junior Member
#5
Also I would not recomend making all these adjustments at one time, I would start with afpr since I assume you dont have one, you may just start there then check your A/F ratio. There will be no way to find out exactly where your problem lies if you jump in and start changing so many things with out testing each and everyone. I would, like you said go on and install the A/F gauge you were talking about so you can get a base line for yourself then do the afpr and check A/F after the reg. install. This will tell the tale.If your still going lean then you will want to check your fuel press. during the run,if all checks good then and only then would I look to the injectors.

PS. if you dont know you can change the afpr with out removing anything else the only problem you may have is one of the allen screws closest to the head.Plan ahead and take it in steps so you know what you got. good luck, if I can help let me know. Michael
87T/C,K&N cone on VAM,255lph,[email protected],[email protected] stock IHI,R.R. in but going out in favor of the stocker,aluminum driveshaft,tranny weights gone. ?whats next?HMM!
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moneypit Offline
Member
#6
Quote:Originally posted by Joe F:
Off the chart lean? Do you have the dyno chart? A graphical representation of the pull would be very helpful in the diagnosis.
I don't have a scanner, but I can tell you this much:
Run 1 shows it starting at the top of the grid- 18.0
Run 2 shows it starting at 15.0, then as soon as the boost peaked it spiked to 18.0 again.
'88 TurboCoupe, '01 Impala, '83 Crown Vic, '95 Jeep Cherokee, 63.5 Galaxie Fastback, '57 Studebaker President... So many cars, so little time.
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moneypit Offline
Member
#7
Quote:Originally posted by Half-Pint:
I would start with afpr since I assume you dont have one
I've got a Kirban AFPR Sitting in the back seat neatly in its wrapper. It just arrived today.
'88 TurboCoupe, '01 Impala, '83 Crown Vic, '95 Jeep Cherokee, 63.5 Galaxie Fastback, '57 Studebaker President... So many cars, so little time.
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Pete D Offline
Administrator
#8
I don't know what your mods are but unless you are running a big turbo, you shouldn't be running lean at 15 psi. The EEC is set to enrich at/above 3K and at WOT.

I'd check/replace the fuel filter if old. Also pull the codes and check out the TPS and VAM readings. I wouldn't recommend starting with VAM adjustments

Backpressure of lack there of is not part of the problem.
Pete Dunham


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moneypit Offline
Member
#9
Codes don't give anything important, the fuel filter is new, the car is 99% stock, the TPS is new and properly calibrated.
'88 TurboCoupe, '01 Impala, '83 Crown Vic, '95 Jeep Cherokee, 63.5 Galaxie Fastback, '57 Studebaker President... So many cars, so little time.
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