1989 caravan air fuel ratio 10:1?

[jefo]

Hey guys,

I installed a wideband in my van to monitor things, and at WOT the afr drops to a little above 10:1. Cruising it sits at just about 14.7:1. Is this normal? Minimal mods are grainger at 11psi, and 3" downpipe with stock exhaust. (and cutout but it wasn't open).

The gauge wideband is an autometer sport comp.

Thanks

[cordes]

It probably shouldn't be that rich at WOT, but the cals do run really rich in boost stock.

[GLHNSLHT2]

the factory cals flood the engine with fuel at WOT. I've seen an 85 2.2 Auto Yorker with an MP computer, 2.5" side exit exhaust bury the wideband at over 10:1. put like 130hp to the wheels. If DWH784 see's this he can chime in.

[1BADVAN]

any other mods? like bigger injectors, or AFPR?

[turbovanman²]

Yep, that is correct, I posted up a few years ago about this problem and got no reply's as I had a stock van that I put a Garrett on and it was 10:1 at WOT.

[Rrider]

Even non TM cars get pretty close to 10:1 at WOT on stock tunes..

[jefo]

Well, it means I can put a big intercooler on, with a bunch of other mods and turn up the boost without having to worry about fuel. And I will gain power from the mod itself, and the better air fuel ratio.

[wheming]

Well, it means I can put a big intercooler on, with a bunch of other mods and turn up the boost without having to worry about fuel. And I will gain power from the mod itself, and the better air fuel ratio.


Adjust your boost increase slowly and you can see that boost slowly lean out that ratio. (And of course watch your other indicators, timing, knock, reading plugs, etc.)

Free power is always good!

my android sent this for me using Tapatalk...

[cordes]

Adjust your boost increase slowly and you can see that boost slowly lean out that ratio. (And of course watch your other indicators, timing, knock, reading plugs, etc.)

Free power is always good!

my android sent this for me using Tapatalk...

Yeah. I bet it'll lean out nicely with the stock injectors still on it.

[jefo]

I adjusted the boost to 13psi which is the max I want to go without an intercooler, and all is well. The afr is still 10:1.

[GLHNSLHT2]

yep because the ECU just ups the injector pulse width as the boost goes up. It only starts leaning out if you go beyond what the ECU can read because now it has stopped adding fuel because it doesn't know the boost level. I don't know why people can't grasp this concept. If the fuel curve is correct adding boost won't lean it out. You need to add more air per psi.

[1BADVAN]

yep because the ECU just ups the injector pulse width as the boost goes up. It only starts leaning out if you go beyond what the ECU can read because now it has stopped adding fuel because it doesn't know the boost level. I don't know why people can't grasp this concept. If the fuel curve is correct adding boost won't lean it out. You need to add more air per psi.

+1 Or lower your Fuel Pressure a bit to lean it out.

[Rrider]

You need to add more air per psi.
So you're saying add an intercooler!

[cordes]

yep because the ECU just ups the injector pulse width as the boost goes up. It only starts leaning out if you go beyond what the ECU can read because now it has stopped adding fuel because it doesn't know the boost level. I don't know why people can't grasp this concept. If the fuel curve is correct adding boost won't lean it out. You need to add more air per psi.

Or when the stock injectors can't keep up.

[GLHNSLHT2]

Or when the stock injectors can't keep up. ain't going to happen on a stock longblock and ECU under the MAP limit.

---------- Post added at 04:38 PM ---------- Previous post was at 04:37 PM ----------


So you're saying add an intercooler!

Yes add an i/c, better intake, ported head, ported exhaust, bigger exhaust. Anything to get more air into the cylinder per psi.

[cordes]

ain't going to happen on a stock longblock and ECU under the MAP limit.

---------- Post added at 04:38 PM ---------- Previous post was at 04:37 PM ----------



Yes add an i/c, better intake, ported head, ported exhaust, bigger exhaust. Anything to get more air into the cylinder per psi.

Absolutely. That would be a real challenge.

[1BADVAN]

ain't going to happen on a stock longblock and ECU under the MAP limit.

---------- Post added at 04:38 PM ---------- Previous post was at 04:37 PM ----------



Yes add an i/c, better intake, ported head, ported exhaust, bigger exhaust. Anything to get more air into the cylinder per psi.

Still if he is still running the mitsu, it might be hard to lean it out they just don't flow any volume.

[GLHNSLHT2]

sorry didn't put bigger turbo in my list of things to do. thought it would be understood.

[1BADVAN]

sorry didn't put bigger turbo in my list of things to do. thought it would be understood. True I should have assumed that :o


The easiest thing would to be lower the fuel pressure, the best IMO would be to get into custom calibrations.

[dwh4784]

the factory cals flood the engine with fuel at WOT. I've seen an 85 2.2 Auto Yorker with an MP computer, 2.5" side exit exhaust bury the wideband at over 10:1. put like 130hp to the wheels. If DWH784 see's this he can chime in.
Yep that was me, went off the scale rich on the dyno. Was a pretty lame dyno setup, no fans so the car was really hot. It was pulling timing at 11psi and it never did that on the street. Still I was surprised it was that rich. The POS cyberdyne a/f guage was reading perfect, 9 lights I think?