When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a 302 from a 98 mountaineer in my 94' Wrangler project. It's running really smooth (little less get-up-and-go than I expects from a 5.0 V8 but still running nice). Idles smooth (around 750-900 rpm) all day, starts first time, etc. etc. Here's what I have:
When the MAF (new refurbed unit) is connected I get the following readings. The car runs fine, but very rich:
STFT1% = around 10%
LTFT1% = 29.7 (doesn’t move at all)
STFT1% = around 10%
LTFT1% = 29.7 (doesn’t move at all)
When I disconnect the MAF I get these. Car runs fine overall but a bit lean. Every now and then we're starved of gas as we're pulling off:
STFT1% = around -25%
LTFT1% = 29.7 (doesn’t move at all)
STFT1% = around -25%
LTFT1% = 29.7 (doesn’t move at all)
Vacuum gauge reads around -18Hg (-8.8 psi) at idle and constant rev. Pretty stable. I've messed with the vacuum hoses while I watched gauge and no obvious movement. The o2 sensors are both new and volt readings on the computer seem within range. Don't have any CATS. Throttle position sensor is good - around 0.85V at throttle closed.
Full exhaust. Original manifolds but no CATs. The MAF is the same MAF as the original MAF. The engine came with that big housing around the MAF. I took it out of the housing and ran a cold air intake into it. Pic attached. As to whether it's the RIGHT MAF, I don't know.
That is more of a hot air intake actually... open air filter in the engine bay, and depending what you are doing with the jeep having the air intake down low like that could be a good way to get water into the motor, but that won't matter at the moment. How far away from the throttlebody is the MAF?
So you have dual exhaust with no cats just mufflers? What size pipe? The stock exhaust on an Explorer is a real cork including 4 cats and whisper quiet mufflers so the engine is going to move some more air now with a free flowing exhaust and that could translate into richer fuel trims. With no cats it's going to smell rich even if it really isn't.
How much run time have you got on it so far?
Yeah, not the best place for the intake. It's my son's daily driver to school and back, no river crossings, so we'll be okay for now. The exhausts are 2.25" all the way with a DIDO Thrush muffler. Got about 20 hours run time on it so far.
If there's more air passing through surely that's the whole point of the MAF - to see that there's more air and adjust accordingly? The MAF is about 10" from he intake. Not too worried about the smell but the fuel trims show that it's seriously rich.
Yeah, okay, I see the logic of that. More air needs more fuel. The weird thing is that long term trims are maxed out but I'm still getting LEAN Mixture codes on both banks. Is that normal with this type of change to the exhausts?
What are the exact code numbers? You do have the front O2 sensors installed in the exhaust and connected right? The rear sensors probably aren't present so there will be codes for those but they don't factor into engine management and can be ignored or you can get some eliminator plugs for them.
So I believe the O2 sensors are wired correctly because I’m getting good voltage readings from them and the rich fuel issue is on both banks. No CATs or post CAT O2 sensors. Codes are below. Most of them are EVAP related.
One thing to try, given that this is a transplant it's possible you have the O2 sensors switched left to right by mistake, so try swapping connections.
P0500 - VSS sensor. That one is important so you need to figure something out for it, in the Explorer it was in the rear axle.
P0443 - Evap/Purge valve
P0453 - Evap pressure sensor
P1451 - Can Purge crt open
P0402 - ERG open too much
P0171 - Lean bank 1
P0174 - Lean bank 2
Guys, I’m still fighting this lean mixture (and rich trims) issue. I’m trying to rule out the EGR stuff because I also have the 402 code. The valve seems fine. Took it out and cleaned it. The solenoid seems to be toast. Took it out and applied 12v to it and there’s no discernible clicking or change to whether I can blow / suck air though either of the ports. BUT when I disconnected it completely I still get the same lean state on both banks and therefore the very rich trims. I expected the 402 code to disappear when I disconnected the solenoid from the valve. Vacuum lines all seem fine. What am I missing??
Did you try switching the O2 wiring left to right?
I did not but I unplugged the right hand one and the voltage for bank 2 #1 dropped to zero so I’m pretty sure they’re not switched.
Today I confirmed that I do actually have good vacuum from the solenoid. I also cleaned the valve and confirmed that there’s no blockage. I tried a new sensor (although the resistance of my old one is good - 3K-300 ohms. No vacuum leaks that I can see. I get a 0401 - insufficient EGR with the valve unplugged from the solenoid, which is what you would expect. Just cannot figure out what is causing the excessive code. oh, I also tried a new MAF for the hell of it. No change. I’m stuck!!
