FAST VE table problem

[level]

I installed the unit last year and the car was running very well. However, there seems to be some sort of gremlin in my car.

I took the car to the track this year and it ran fine. I put the car in the garage after driving it home and when I went to start it a few weeks later, it starts blowing black smoke out the tail pipes. I looked at the Actual A/F and it reads in the high 9's low 10's with the same program that use to read in the 11.7's (WOT). I had to reduce the VE table dramatically to lean the car out so it wouldn't foul out the plugs.

I also noticed that the FAST was reading PSI way low at Vac. (around 5 when actual was about 13). I replaced the map sensor and didn't see a change. Frustrated, I borrowed another unit (including the O2) installed my original program and the results were the same. I have to idle around VE of 12-14 to make the car idle. These numbers use to be mid 30's; this trend continues throughout my VE table. Does anyone have any ideas as to what can be causing this?

 

[TurboJim]

Well, if actual vacuum was 13 but read 5 the car would be reading from the load area of the VE table. You need to find out WHY the vacuum reading is low. EGR stuck open? Hard plastic line to the MAP sensor cracked? Mouse eat the vacuum hose? A leak in another vacuum line close to the MAP line, close enough to cause a low reading? Wrong TYPE of MAP sensor? (2 vs 3 bar) Bad sensor ground?

I think you find the cause of that low reading, you'll have the solution to your problem

 

[TurboTR]

I think your actual was 13 inches Hg, not psi, no?

TurboTR

 

[level]

It was PSI. Tonight I'm going to look for a Vac leak between the MAP and source as suggested in the first reply.

 

[stevec]

Gremlin

Double check all the electrical connections to make the map sensor read through the factory harness the jumper connection. I have seen several problems arise out of using the stotch locks instead of soldering. Also check the key off MAP reading sould be 0 and neg at idle.

I even go as far as calibrating the map sensor against a 1% accurate pressure guage. All you need to do is remove the vac line to the map sensor and get anadjustable regulator and run one side to the map sensor install a pressure guage on the other fiiiting at the regulator, hook it up to compress air source and apply pressure to the map sensor. Start at 5 psi on the pressure guage and see what the map sensor is telling the ECU. BTW you need to hook up the computer and be linked up with the ignition key on.

Keep turning up the pressure 10, 15, 20, 25, 30 and see what the ECU is seeing. They sould be within 1 lb of each other.

Also wiggle the jumper connection and make sure the readings dont change. If they do you have a bad connection somewhere.

Steve C

 

[TurboTR]

Well the reason I ask, if your engine is pulling 13 psi of vacuum, that's 26.5 inches of mercury (nearly 1 bar), which would be about 8 more in. Hg than even the stock engine pulls at idle in park, according to most people's gauges. ~ 5 psi on the other hand would be about 10 in. Hg of vacuum, along the lines of a somewhat cammed up engine. FWIW.

TurboTR

 

[TurboJim]

Again, my problem is with the difference between actual and measured. Low vacuum measured will put the motor under load to the ECU and fuel it accordingly.

 

[level]

Well, you guys have given me some ideas to check out. Since tomorrow is my day off, I will dig some more to find the probelm. I will be in touch. Thanks for your posts.

 

[level]

Just curious, what sort of AF are you guys running at WOT. Is there anyone running 83's that could give me a "general" ratio?

 

[TurboTR]

At high boost typically around 11.5 to 11.8 or so. No compelling scientific reason why, it just seems to work pretty well.

TurboTR