maachine

ok so i hate to start another thread about code 25, but i am lacking information. should be quick and easy if anyone knows the answers.

from the FSM
1. check grounds. this should be no problem
2. open E1 circuit. how do i check this? check it for continuity?
3. open fuel injector circuit. how do i check this?
4. injector blockage. possiblity but i doubt it. truck runs way too well for this
5. open or short in O2 sensor wiring. look for loose connections or broken wires
6. Bad O2 sensor. anyway to test them first? probably save this for last
7. check ignition system. no sweat here, check gap in dizzy? what should it be? what should the timing be set at? read somewhere use jumper, set to 10, pull jumper and it should drop to 8. correct?
8. engine coolant temp sensor. whats the ohm range when cold?
9. volume airflow meter. cant find a source on how to test this either
10. ECM (bad?). again truck is running way too well for this to happen

ok this is my neighbor's RV. he is 79 years old and he just bought it. he complained that gas mileage was bad. around 9 miles to the gallon, when new it should be around 15 if i recall correctly. no engine light when he bought it but his son was backing it into a place and ran the tail pipe into the ground causing a plugged exhaust and creating the code 25. i'm guessing bad O2 sensor, but before i start spending this guys money, i want to check everything else first. thanks guys

oh anyone know where i can download a FSM for this thing? a lot of the links floating around the internet dont work anymore

Co_94_PU

iTrader: (-1)

Same one I linked ya before I think
http://personal.utulsa.edu/~nathan-b...fsm/index.html


In my case it's caused by dirty contacts in the plug between the harness and oxygen sensor, just needed cleaned, tightened and water proofed.

maachine

before? never got that link before.

thanks bro, you are all knowing around here arent you? i'll start digging through that. and ya that was going to be one of the first things i do, clean the connector to the o2 sensor

Gamefreakgc

I chased a code 25 for months. Hope it's an easy fix for you. I'm not on yotatech as much as I used to be but pm me if you can't get a fix. DO NOT throw parts at a code 25, you'll end with with the same issue and hundreds of dollars less in your bank. Here's a link of the path I took (some things that I did aren't posted though):

https://www.yotatech.com/forums/f116...-3vz-e-258926/

maachine

thanks for the link, i'll look it over in a minute. i did find that the volume air flow meter is not within specs. with the valve fully closed it should close a switch to create continuity between pins e1 and FC. we are getting nothing. its sitting on my work bench now. i'll tear it apart and take a looksy inside and see why that contact isnt closing all the way.

anyone ever fully disassemble a VAF before? can it be done?

Gamefreakgc

Yeah, plenty of threads about it. You'll find two camps of people: those who say you should tweak it for various reasons and those who say don't touch it since there's no guide or procedure to know what exactly you are doing. I fall in the latter. Just do things at your own risk and be prepared that there's a chance you might need a new one.

maachine

well it appears we need a new one anyway. i told my neighbor that we would check everything else out before we started buying parts.

the seller did replace a lot of stuff before he sold it to my neighbor. even the VAF meter looks new. so i glanced over the ignition system and didnt see anything obvious. spark plug wires are new so i assume the plugs are new too. new air filter. bunch of new vacuum hoses. glanced over the grounds too. didnt look corroded and they were tight. sounds like there is a misfire every so often so i'll check the diz and timing tomorrow, but that could be caused by the lean condition couldnt it? i also need to check for vacuum leaks, didnt do that yet.

so the only things i didnt check on that list is injector blockage, open e1 circuit, and open fuel injection circuit.

that was some laundry list you have going on that thread gamefreak. that sucks but at least you found a solution.

Gamefreakgc

Unless the RV has been sitting for a long time, it's probably not a bad injector. More likely to be a wiring issue if you think it's the injectors.

Does the engine shake at all? Any kind of major side to side motion is a sure-fire sign of a valve terribly out of adjustment, especially at low or around 800 RPMs.

maachine

the thing runs great actually besides that slight miss. its the light and the bad gas mileage thats annoying him the most. it has been sitting a while. which is why i think the VAF is bad, the switch is probably stuck.

it only has like 54,000 miles on it. so i doubt its a bad valve. but i'm starting to think it has a ton of new parts on it because of this code 25.....the guy couldve reset the computer right before he sold it.

maachine

just to clarify something i said that was wrong earlier. the VAF is good. i forgot how to use my multimeter. continuity does not mean infinity (which the FSM says to look for) infinity is an open circuit (on my digital meter is OL), not a closed circuit (which would be continuity). i was backwards.

maachine

also the FC prong sends power to the fuel pump relay.......so if the fuel pump is working.....most likely that FC switch in the VAF is working. which in my case, it is

the article i read that made me realize i was wrong

http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

Co_94_PU

iTrader: (-1)

Dur sorry mine is 21 not 25, could still be a bad connection just the sensor data not the heater power.

O2 inspection is covered under the engine->MFI section and is done at the diag connector.

E01 E02 and E1 All use the same ground point, located at the rear of the passenger valve cover. There is an internal bypass in the ECM incase one of the wires or the splice point is damaged. Test is a voltage drop test.

Open circuit in the injector wires is a voltage test, #10 & #20 to E1 at the ECM 9-14v (Key on).

Think thats all the direct questions? Nope missed a few,all the specs are in book.Don't overlook the engine->Troubleshooting lists Poor fule econ' should be lots of fun it's 22 items long I can rule out one of those odds are you don't have a leaky injector if you have a lean code too.

maachine

i'm gonna fool around with it more today. i'm starting to think clogged injectors due to the fact that it does sit for periods of time. thank you for pointing out the other guide to go through. and ya, o2 sensor is good and so is the VAF.

maachine

alright, just to sum things up. worked on the rv for a bit. found some air hoses loose. tightened those up. checked the grounds even better, they were good. coolant temp sensor, o2 sensor, and VAF are good. ran my unlit propane torch around most vacuum hoses, no vacuum leaks. put the timing light on, found timing to be set to 5*. hooked up the jumper and it jumped up to 7*. set timing to 10*, pulled out jumper and its set at 8* now. so maybe that was the issue. reset the computer and ran the rv for about 20 mins and no codes popped up. so hopefully thats it. i told him to run seafoam through the next couple of gas tanks.

Gamefreakgc

Code 25 is a two trip code. The first time the ECU detects it will not throw a code. Only after turning off the vehicle and the ECU detects it a second time will it come up. It's dreadfully annoying, sometimes my truck would go a week before the code popped back up.

Co_94_PU

iTrader: (-1)

test mode Eg2-179.

maachine

thanks CO 94. i told my neighbor that i've read threads that guys have driven their trucks for 5-6 days before the code ever popped up again. i told him to expect it and that i'd plug away at it more if it does come back. i think it has some exhaust leaks, so i'll go through the exhaust system if the code comes back, pop the plugs out and look at them, open up the dizzy and check there too. i didnt go through the ignition system like i would normally have except i didnt have much time today.

maachine

oh and thanks gamefreak

maachine

ok so neighbor told me the code came back. when i find some time im going to go through the exhaust system and tighten things up. my neighbor told me that this time (just like the first time) the frame was being flexed when the code popped up. so i'm wondering if some flexy action is taking place, pinching a wire......opening up an exhaust leak.....not sure.

do you guys know how long it takes the diag system to run a cycle? for example, if an exhaust leak were to open up.....O2 sensor goes nuts......how long would it take to trip the check engine light?

Co_94_PU

iTrader: (-1)

It's part of the description. It has to happen for more than a short bump, 90 seconds.
Don't "fix" anything just do the drive test per the manual, if it doesn't light up it might be a wiring issue. Loose connector on the o2 or injectors. If all the the connectors and wiring are good I'd suspect the gas and/or injectors. Rv's are notorious for sitting a long time with gas in the tank, which of course leads to varnish induced clogs and sticky injectors.