Morgan_marty

I have used the search function.. I just kind of need to talk this out and get some input from you guys. I've read so many posts on this I feel like i'm going cross-eyed

I'm trying to find a general direction to go in with my truck. I have a 1994 pickup 4x4 3.0L. I just recently purchased the truck and the truck has had a new motor put in around 800-1000 miles ago along with a newly rebuilt transmission. It started out that the truck had a bad stutter/miss and was throwing code 25. I have done the following:

-Replaced fuel filter (Engineer was crazy for putting it there!!)

-Replaced all Vacuum Lines and made sure they all had a good seal (some of the vacuum lines had previously been installed in the wrong place)

-the previous owner had a used air flow meter installed. I was tinkering around and learned the shop (yea he paid to have a shop install the air flow meter)that installed the AFM apparently thought an air filter was optional. (Installed a new air filter and this helped quite a bit, naturally)

-Replaced all spark plugs with NGK plugs and found a wire that had a rubbed spot on it

-Replaced spark plug wires

-Distributor looks new

-Coil looks like it was replaced by previous owner looks very new

-Oxygen sensor had a bare wire Replaced O2 sensor and this helped the problem quite a bit. (Denso)

-Pulled the intake tube off and the butterfly valve was clean and free of carbon buildup

-Checked and cleaned all grounds. Positive side looks good, i'm going to redo the hot wire that goes under the fuse box as it does look a little suspect.

Now we get to the nitty gritty... Truck runs good idling and at high RPM. If you hold the throttle just above idle while sitting still(guessing around 900-1200 RPM) it has a stutter. It will also stutter/jerk/buck while driving around 45 mph and barely give it gas (pretty much the same as sitting still 900-1200 RPM). Truck started throwing code 71 which has to do with the EGR stuff... I took the vacuum line off of the top of the EGR Valve and plugged it... same situation stutters at low RPM's above idle. I also jumped the terminals in the diagnostic box like you would to time the truck and no change, still stutters.

What do you guys think? Where should I go with this next? I'm open to any ideas as to where to go next with this! I do appreciate all or any help that you can offer!

Thanks! Marty

Morgan_marty

A couple other things to add...

-not sure if it's related but when I turn my blinker on sometimes my speedo will bottom out

-it seems as though it was a little worse today stuttering through a wider range but it could have just been my frustration picking it up more

-not losing any oil

No oil to be found in the top of the radiator

This is all I can think of right now.

Marty

wyoming9

iTrader: (1)

You should post where you are Help could be close at hand .

You did the plugs and wires but no cap and rotor??

Is it more of a miss ??

I would check my fuel pressure .

Funny person spends the money on a rebuilt engine and trans and does not do the fuel pump.

Could have been the type to drive around on fumes.

Morgan_marty

Funny you mentioned the fuel pump, I was just driving to the store and got to thinking about it. This is only the first tank of gas that i have run through it. I just hit around a quarter of a tank and it seems as though the problem has gotten worse the lower I get on gas. You are correct, I did the plugs and wires but did not mess with the cap and rotor b/c the rotor looked new.. guess I should jerk it off and check the contacts anyway! Guess i'm going to take a dive into the fuel tank next and check that situation out. May find a tank full of rust!
Fayetteville, NC btw!

Gevo

Stuttering at 900-1000 RPM, and overall not workign well in that range can do with your TPS adjustment. I played around with mine a LOT and it should be easy enough for you to check. Follow the FSM and make sure the TPS tells the ECU it's out of IDL within the specified location. If the tps is way off, you can be on the throttle a bit and the ECU would still be thinking it's in IDL, and all kinds of funky happens.

Morgan_marty

Alrighty, Thanks! I'll look into that tonight when I get off work!

Gevo

I was thinking more about this and.... I wouldn't call it stuttering, for me it was just a very rough running engine.. so, I dunno if this applies.. regardless, check it!

scope103

Did you actually check the ignition timing? Timing off can cause all of your symptoms, but the main reason to check it first is because it is so easy (compared, for instance, to checking the fuel pressure). A timing light is so cheap ($20) it's the sort of thing you should pick up with your first socket-wrench set.

I assume that your code 25 is now cleared up. Plugging the EGR system will not make your code 71 go away.

Start with the easy diagnostic stuff, and work your way to the problem. Replacing parts at random hardly ever solves the problem.

Morgan_marty

Have not checked the timing as of yet, I'll put that on the list along with the TPS. I need to pick up a timing light, to this day i've never needed one but I believe it'd be useful... now as far as the timing goes, if I have no tach how to I verify what i'm idling at?
The only thing with the timing that wouldn't make since to me is the problem doesn't seem consistent as of right now. It seems as though it is progressively getting worse, not sure if that has to do with the fuel getting low or a sensor getting worse. If it was a timing issue wouldn't the problem be consistent? (still going to get a light and check it because at this point I can't trust someone else that apparently thinks an air filter is optional! Any advice on a timing light to get?

scope103

This is all you need: http://www.harborfreight.com/xenon-t...ight-3343.html
While you're at it, pick up http://www.harborfreight.com/7-funct...ter-98025.html You'll want one sooner than you think.

bbrideau

hows your battery and charging system. You mentioned when you turn your signals on your speedo goes to 0. If it's electronic speedo and you turn the signal lights on it shows a voltage drop, usually. I know when my alt started to go the tach was the first thing to start acting funny minus the idiot lights coming on. (check to make sure your park brake and charge light are functioning as well)

You could have a dead cell in the battery or a weak alternator, low voltage will cause all sorts of funny things to happen. When my battery got old and started to act funny it was getting dark and late so it was cooling off and i was stumped about what my issue was (cant remember the issue now) but i decided enough was enough turned heater on full blast and threw my high beams on at the same time. motor would cut out temporarily, tried it a few more times to make sure it wasn't a fluke. Changed battery out with a red top optima. problem solved.

not saying it will fix your problem, sounds like there could be more to it than that but it is one less thing to rule out and a multimeter with long leads and about 15 minutes of your time is an easy and cheap thing to do just to make sure. (don't trust the gauge on the dash for voltage, its mostly for looks)

Morgan_marty

Yea, been thinking about that as well but charging system/battery seems to be functioning normal. I do have a battery gauge and I've been watching it pretty close and doesn't seem to present a problem, I'll try overloading the system with everything once I get home and watch the battery gauge to see if there is any problems with that. I think the blinker/speedo issue may have something to do with the small hot wire going from the battery to under the fuse box. It seems a little suspect... for all I know that could be the WHOLE problem... rebuild that wire and see what happens

Morgan_marty

Status update: Just got home and took my AFM off going to start the process of pulling the TB off and checking the TPS/adjusting/replacing. I thought this was a little bit off, but I need your opinions. The hoses that connect to the bottom of the TB was plugged and not installed (see pictures) What does this mean?

Disclaimer: I'm doing this from my IPAD so I couldn't draw circles around the plugged lines but they are pretty visible!


What's ya'lls take on that fun stuff!?

Morgan_marty

Note on the side closest to the firewall, you can't see it but there is nothing plugging the port where the line attaches to on the throttle body...

Morgan_marty

Dropped the tank tonight and it was pristine on the inside, I did however break the metal fuel line that goes in the tank... Barely moved it and it started spraying...
Tips was good, and engine coolant temp sensor is good... Back to the drawing board

Punchy

Those hoses that should be connected to the throttlebody are cold engine idle up.


As the engine heats the coolant flows through a valve in the TB slowly closes lowering the idle.


It may be bypass because coolant is leaking into the throttle body.

RSR

FWIW, Gevo had a writeup on adjusting the throttle body coolant portion in his build thread.

Terrys87

iTrader: (1)

Check your fuel return line. I see them clogged a lot. Probably not causing your idle problem but could put a strain on your fuel pump. I remove the gas cap and just bump it with an air hose, just enough to see if I can hear the bubbles in the tank.

Gevo

Interesting, I didn't know this about the coolant flow. What I read was that it is to keep the air from frosting in cold weather.

Also, I did take it all out and clean it. Improperly maintained coolant seems to clog everything up. It's not that big of a job, take the throttle body out, clean every orifice and put it back with the coolant hoses. I would bleed the coolant out from that line that connects to the throttle body before connecting it back. I don't think this is causing your issues though.

You said the TPS was good, how did you check and/or adjust it? As per the FSM?

Morgan_marty

Actually I had already bought a TPS so I just replaced it and adjusted it within specs. just as the FSM calls for. I'm going to get the fuel line fixed, hoist the fuel tank back under the truck and check the timing.