wayshegoes

Is there a list somewhere, that has the recommended values for the sensors, recommended for a factory original car? I can read using my cable but just not sure what is the optimal value for said sensor


thanks in advance,

Jeff

ASE doc

Usually when we look at scan data values, we're looking for the cause of a fault, such as lean or rich AFR. In this case, we look at fuel trims which read as Block Learn(Long Term) and Integrator(Short Term). These read 128 at zero correction and range from 100 up to 156 100 being a rich indication(removing fuel) and 156 being lean(adding fuel). Bock Learn Cell is the cell in which the engine is operating based on engine sped and load. ECT reads in degrees F. TPS on the 88 should read about .5 volt at closed throttle, 4.5 at WOT. Oxygen sensor will toggle in closed loop between .200 volt and .900 volt.

MAF can vary in how it is displayed. It might be Hz, volts, or grams per second. I usually only look at MAF if there is a lean condition. MAP, if yours is Speed Density, should be about 4.5 volts key one engine off and about 1.6 volts at idle. The factory service manual has a list of PIDs and their normal ranges.

Is there a particular issue you're trying to solve? Any fault codes?

wayshegoes

thank you for the reply, no codes, the issue is my starting problem, i have posted in another thread

when car sits over night, go to start in morning, i have to crank the car 3-4 times, each crank is for 5-6 seconds or longer, and eventually it stumbles to life, rest of the day it will fire right up, fuel pump primes when key is turned, i dont know my fuel pressure off hand, as i was chasing this problem last summer, but it was good, i will check this weekend

i do know that my pressure bleeds off quickly when key off, changed to a new adjustable FPR (old one the diaphram was leaking) injectors are bosch 3, maybe its the check valve in tank?

my CSI is removed, have a chip adapter from tpiparts that is setup for a removed CSI, but still many long cranks, i have been reading and reading, just cant get a fix

oh, i also replaced my CTS, no change in the starting

was told a prom from a 89 may fix it, but that is what the purpose of the adapter i bought is, isnt it?


Help please

Tuned Performance

iTrader: (92)

With 89 programming 8drp are required until injector pulse . These values can be changed 1-7 to help in faster startup.
The fast bleed off will be a issue, injectors , for or pump.
It's normal for bleed off over 10 min.

wayshegoes

I am not sure what that means

Should I get a used PROM from a 89, if i can find one

or is my adapter not setup correctly or just not designed to work correctly?

Tuned Performance

iTrader: (92)

The piggyback adapter will work fine but can be better

There is a delay in starting 5-7 sec on 89 programming unless you enable the injectors earlier . Stock it needs to see 8 distributor reference pulses at 400 rpm or higher to enable the injectors.

ASE doc

Yeah. The 89 had gone away from the CSI in favor of cranking fuel pulse from the 8 injectors. Sounds like either inadequate pressure at start up, or just not enough cranking fuel pulsewidth. The drop in pressure after pump shut off indicates a possible bad check valve is pump. You can test by using pinch off pliers at the rubber sections between the engine and frame underhood. You need to jumper the fuel pump relay so you can control the pump manually.

If pressure holds with the supply side pinched off, the check valve is leaking. If it holds with the return line pinched off, it's the regulator. If it won't hold with either one pinched off, it's a leaking injector or regulator diaphram. This drop in pressure, or rather the time it takes for pressure to come up after you start cranking, will make for longer crank time but isn't the reason for it taking three or four tries to start the engine. Not if fuel pressure is normal while cranking.

Data values aren't real useful on cold start, except perhaps injector pulse. What you would be looking for is a value close to that of an 89 without CSI. However, since you are using an aftermarket piggyback module to simulate the higher cranking fuel rate, it probably won't show up on scan data. O2 voltage isn't really going to help since the sensor won't be hot enough to operate. One quick test I would try, just to be sure it's just fuel would be to spray a little starting fluid into the throttle body before you try starting the engine to see if it makes a big difference.

Look at your warm engine fuel trims to be sure you have the fuel pressure set right for the new injectors. Make sure the MAF is clean and no air leaks to the TB to be sure you are getting correct MAF value at cranking and cold start idle.

You would need a labscope, to verify the cranking fuel pulse at the injectors, to know if the CSI replacement module is working properly. I would address the fuel pressure drop, just because.

JA411

Usually fuel pressure leaking as said by Ase doc. Test pressure at rail while running, leave gauge on and time pressure drop. As said before you can rekey up to bluid pressure and pick off or block off return and time again. If it holds better usually check valve in fuel pump. If the same drop usually regulator or injector leak. Does it black smoke when it does fire up and run?
Joe

wayshegoes

thanks for all the replies

I will start with fuel pressure, I went through this last year but never got a resolution

I will check pressure while cranking and do a bleed off test

is the check valve a part of the pump or is it separate ? does it involve dropping the tank?

ASE doc

The check valve is in the pump and yes to replace it you need to drop the tank. There is also either a short section of rubber hose or a pulsator between the pump and the metal line of the fuel tank unit. The rubber hose can become perforated and leak. The pulsators are known for developing a leak.

Tuned Performance

iTrader: (92)

if the pulsator is in place replace it with a rubber hose and clamps.