1989 Daytona Shelby cut out/fuel cut?

[ShelbyMopar]

Hey all,

Interesting scenario here, I'm thinking its possibly the distance sensor but heres what I've found:

Bone stock, all original 1989 2.5 T1 Auto.

At approx 4000-4500 RPM, the car acts as if it is hitting fuel cut. I've checked the fuel pressure, the regulator is working properly and there is fuel there.

Now, it does have the digital dash, which is interesting because it was working great, then the speedo started to act up and is all over the map now. Most of the time it doesn't read properly now, but it was working today and only cut out once in 2nd gear (A413).

Checked plugs, Cyl 1 and 3 seem a bit lean.

Boost pressure is a low 5 psi, so it isn't overboosting.

Things I've swapped with known working components that has made no difference (I have alot of spare vehicles around)

HEP
Coil

Codes are 47 and 55, not sure why the 47 is there but it has been charging normally.

Thoughts?

[turbovanman²]

Check TPS and grounds.

[ShelbyMopar]

Swapped TPS for known good unit, made no difference. Checked all the grounds and added one to the fuel rail just for safe measure (had similar problem on another car) and no difference...

Disco'd all the purge system crap and removed it, re-checked all vac lines, didn't seem to find anything wrong or make any difference.

Same codes... Just 12, 47, 55.

Next thing I am going to try is fuel filter, not sure when the last time previous owner did the filter. Air filter was super clean. I'll probably check timing as well next time I can visit the car.

[Orangetona]

Honestly, are you sure its fuel cut? Or will it just not rev higher than that? Id almost say it could be cam timing.

Also you could have an intermittent charging problem. If so I can see it causing problems because the electronics arent functioning at the right voltage.

[ShelbyMopar]

I'm almost positive its fuel cut. It'll rev higher, if I back out of the throttle. Anything above 75% throttle seems to make it cut at around that 4200 RPM mark.

I checked the timing roughly (pulled distributor cap and timing cover while #1 piston was TDC) and it looked like it was right on. Usually I can hear it if the timing is off a tooth even on the cam. I thought about the charging system too, but one of the battery connectors was a bit corroded, so I cleaned it up and I imagine that code isn't even there anymore.

[bakes]

Speed and distance sensor crapping out.

[ShelbyMopar]

That was another one of my thoughts. Does the digi-dash use any special sensor, or is it the same? It's the first digi-dash car I've worked on, it looks like there is an extra cable from the throttle assembly to some kind of sensor. Haven't ever seen it before.

Its not my car, I only see it on weekends for the most part. Its a younger brothers car, helping him fix it.