3900 Tuning datalogs

[Guest]

I believe I have found the cause of the difficulty I'm having with tuning the engine. Throttle tip in is problematic regardless of AE table adjustments and fuel injector size changes.

The MAP load variable is constant suggesting there is no MAP signal variance with accelerator change and that would be in unison with the apparent leaning out that is occuring as revs climb and the need to pump the pedal to get the engine to rev through its full range with a low MAP signal reading. I suspect a bad MAP or poor connection.

I don't know how to change the MAP volts to a kpa reading if it's possible. I'll try to get some more data logged before I leave today since it will be a while before I can work on it again.

I attached a file with a run using the Beretta code also to show that there is variance in the MAP signal using the 1 Bar MAP although the signal voltage appears to be a little on the high side. I'll check for vacuum leaks and maybe disconnect the wastegate lines since I had to use sealant to help properly seal the NPT fittings which leaked regardless of the torque on the retaining bolts.

Take a look at what I have and tell me what you think is going on for those who can interpret it. I finally succeeded at connecting to the ecm with the emulator though I have not been able to emulate and datalog simultaneously as the instructions imply I can.

[Scott_68B]

Are you sure you have the MAP connected directly to a port in the manifold? When I first did my conversion, I had the MAP connected to a port off of the TB that didn't provide a constant source of vacuum and I was getting codes telling me my MAP was bad and the engine exhibited very similar symptoms to what you are experiencing. When I connected it directly to the manifold, my problems went away. Just a thought.

-- Scott

[Joseph Upson]

Are you sure you have the MAP connected directly to a port in the manifold? When I first did my conversion, I had the MAP connected to a port off of the TB that didn't provide a constant source of vacuum and I was getting codes telling me my MAP was bad and the engine exhibited very similar symptoms to what you are experiencing. When I connected it directly to the manifold, my problems went away. Just a thought.

-- Scott

Not a chance, the vacuum/boost gauge is connected to a "T" fitting off of it so I would know if there was no vacuum at the sensor.

[IsaacHayes]

Hmmm. Verified the wires are all soldered/connected well for the MAP?

Here is how the def file for a 3100 converts volts to kpa. This is for a 1bar MAP though so the ratio will need to be changed to correspond with 2 bar.

Operation: Multiply ([X*Factor] + Offset)
Factor: .369
Offset: 10.33
Unit label: KPa

You can hit F4 then click "Edit ALDL Def file" and check out what your MAP one says and maybe try putting that in there after you have figured out what needs to be changed for 2 bar.

[IsaacHayes]

Found this: here
1-Bar MAP -> kPa = ADC * 0.369 + 10.415
2-Bar MAP -> kPa = n * 0.78431 + 8

[Joseph Upson]

The wires should be fine because the 1Bar MAP along with the A1 code showed the proper response, in addition to that I just recalled how smoothly it reved in the video I posted on streetfire toward the end. I'm also recalling previous suspect problems with that particular 2 Bar MAP in at least two other applications where I was suspecting it or got a code. The last was during an attempt to setup the 1985 Fiero ECM for turbocharging, I had to get the car running with a 1 bar MAP first, then after shutting it down I could install the 2 Bar MAP. It would run as long as I held rpm up around 2500 or more but once it shut off it would not start again unless I repeated the sequence.

I performed two more logs and clearly the MAP reading is not increasing with the TPS sensor and that is causing the lean out stall, and detonation. The pump shot is what allows it to rev up to higher rpm but when you try to hold it there it fades within seconds.

I could post more logs but it isn't necessary because both show the same thing with a slight fluctuation of a few tenths momentarily and that's it. The fact that a voltage is showing up at all suggests the wires are fine and the MAP is the problem. Even if the code were somehow set to a 1 Bar MAP if that's possible in TGP code that should be defaulted for 2 Bar, that still shouldn't stop the voltage/Kpa from varying with throttle input. A member on the Z24 site took care of the MAP conversion units by sending me a modified Ads file.

[IsaacHayes]

Ah so suspect MAP sensor.

(thinking out loud here):
There is also Engine Air Flow grams/sec not sure how that is generated since there is no MAF on the TGP... Must be calculated.. no?
And Cat Conv Temp.... does the TGP have a pyrometer??

[Joseph Upson]

Ah so suspect MAP sensor.

(thinking out loud here):
There is also Engine Air Flow grams/sec not sure how that is generated since there is no MAF on the TGP... Must be calculated.. no?
And Cat Conv Temp.... does the TGP have a pyrometer??

I installed an EGT sensor. The MAP related input is the only thing malfunctioning, I suspect if it was the ECM or the wiring the 1 Bar MAP with the Beretta code would not function properly either but that wasn't the case and this appears to be something that occured while the car was sitting.

[Joseph Upson]

I forgot about this thread so I'll start the tuning continuation here. I confirmed that the old MAP sensor was bad.

I speculated in a previous dicussion that I may need to increase the size of the hole I drilled in the Northstar throttle body to make a passage for the IAC air to enter the manifold since that parameter was not included on the adaptor plate.

I just cranked the engine up with part of the intake plumbing removed and noted it seemed to be sucking air pretty hard but for the first time on the same tune I left off on with it needing to warm up to avoid stalling, it nearly immediately idled normal, then I realized that I had two vacuum leaks present from items I forgot that I had disconnected so it stands to reason as such. I thought the hole was a desent size but I'll have to check to make sure it is at least the same diameter as the IAC passage.

In the mean time the alternator is still a problem, I replaced it but I'm still not sure how to connect it now. I have terminal F and L and a 5 volt regulator plus resistors to drop down in the milliamp range for added safety when applying voltage.

With the alternator terminal F and L disconnected the voltmeter goes from left of 13 volts to right of the 13 volt mark on the voltmeter although technically it is not turned on, once the engine is running suggesting it is working despite the abscence of power input to the regulator.

I'm going to install my additional gauges and start tuning while driving tomorrow.