"Long_Voyager94" (yourenotavalidusername)
11/05/2020 at 17:54 • Filed to: rallyvan, Issues
2
13|
"Long_Voyager94" (yourenotavalidusername)
11/05/2020 at 17:54 • Filed to: rallyvan, Issues | 2
| 13 |
Alright boys and girls, time to pick your brains (no I don’t mean get a Covid test).....
I’ve been enjoying the performance from my 98 3.8L swap in my 94 shorty. But I’ve noticed 2 issues.
Issue 1: The newer 3.8L makes all it’s power/torque under 4500rpms, basically falling on it’s face after that point, so my transmission holding gears to 5500 rpms is just an exercise in making noise and burning fuel. What I’d like to do is find someone who can “reflash” my TCM to lower the shift points and force the trans to hold gears to make better use of this engine’s low end.
Issue 2: I have noticed it runs quite rich, especially in the higher rpms. Normal driving isn’t noticeable, but WOT is rich enough to garner black smoke out the pipes.
I’m thinking this may just be a faulty FPR as I had to use one I had sitting on the shelf, so that’s going to be my first course of action. From there I will have to see what happens.
UPDATE:
After backprobing the Throttle Position sensor as
!!!error: Indecipherable SUB-paragraph formatting!!!
suggested, I decided to do the same to other sensors.
Turns out my MAP sensor is not putting out the correct voltage per load, even at idle it is weak. So I will start by replacing the faulty MAP sensor and go from there.
atfsgeoff
> Long_Voyager94
11/05/2020 at 16:25 |
|
Check your throttle position sensor for full range
Future next gen S2000 owner
> Long_Voyager94
11/05/2020 at 16:34 |
|
Time to get into tuning! Get you a laptop and some software. I once didn’t watch a video on YouTube on how to tune. How hard can it be?
WasGTIthenGTOthenNOVAnowbacktoGTI
> Long_Voyager94
11/05/2020 at 16:34 |
|
The trick is to just add more air if you’re running rich. I would suggest nitrous .
|
Long_Voyager94
> atfsgeoff
11/05/2020 at 16:37 |
|
Hey, didn’t actually think of that.
I’ll have to back probe it tonight and see if I have full range!
|
Long_Voyager94
> WasGTIthenGTOthenNOVAnowbacktoGTI
11/05/2020 at 16:38 |
|
|
Long_Voyager94
> Future next gen S2000 owner
11/05/2020 at 16:39 |
|
Weird OBDI-OBDII changeover year.........So quite hard?
Highlander-Datsuns are Forever
> Long_Voyager94
11/05/2020 at 16:53 |
|
So you are rolling coal with a 3.8 gasser? I don’t see a problem here.
Snuze: Needs another Swede
> Long_Voyager94
11/05/2020 at 16:59 |
|
Reverse rising rate fuel pressure regulator? As in , it lowers the fuel pressure as you increase throttle to counteract its enriching tendencies.
Victorinoo
> Long_Voyager94
11/05/2020 at 17:04 |
|
If it has OBD2 or 1, plug in your obd diagnostic tool and look at the long and short term fuel trims. Focus on the short term trims as the you dri ve around and RPMs climb. If you see the short term begin to go negative, then you know the car is trying to pull fuel, meaning you’re running rich. If this is the case you now need to know why you’re running rich. Also don’t do this at full throttle as you’ll go into open loop and skew the results.
A bad FPR could be the cause, but let’s diagnose first. Place a fuel pressure gauge on your fuel rail while you perform the obd fuel trim observations. Compare this to the values that are acceptable in the service manual. This will allow you to rule out fuel pressure as a problem.
Sovande
> Long_Voyager94
11/05/2020 at 17:22 |
|
Swap the rear end.
|
Long_Voyager94
> Highlander-Datsuns are Forever
11/05/2020 at 17:46 |
|
Well I mean, it doesn’t bother me other than it’s not running optimal....
|
atfsgeoff
> Long_Voyager94
11/05/2020 at 22:01 |
|
Glad to hear you found the culprit! Damn MAP sensors can cause all kinds of weird symptoms
|
Long_Voyager94
> atfsgeoff
11/06/2020 at 07:00 |
|
Hopefully that is.
The MAP is clearly not doing it’s job, so it’s a starting point. If it solves the rich issue, I still have to figure out the trans retuning.....