TBI Woes

[Techlight]

Hi All,

So I took the jeep out and was splashing in some puddles a few weeks back. Motor started to get wet and so I parked it. When it was carbureted it would always dry out and no problems. The Howell system seems to have freaked out.

It's running rich it seems to me...alot of wet fuel coming out of the tail piple and black carbon and the mechanic said it was running rich (more on this in a minute). It's throwing code 12 and nothing else. I'm checking it with the jumper and watching the light flash. It bogs down if I step on it and then kinda lurches forward. It's generally running rough like the timing was off or something. I parked it for awhile and then my Honda was stolen (again) and so i need the jeep.

I checked for vacuum leaks and intake leaks but found none. I took it to a reputable mechanic in my area and they had if for 5 days and were back and forth on the phone with Howell and they ended up giving it back to me because they couldn't figure it out.

They checked: TPS, MAP, O2, IAC, timing, dist play, back pressure, engine temp, fuel pressure. All supposedly good, but it's still throwing code 12.

Any ideas or help would be great...or if you know a good mechanic in the Lancaster CA area.

The motor is a reman stock with a mild cam. About 8-10k miles, Howell CA TBI, and the Team Rush Ford cap and rotor. The rest is all stock.

The system used to run great when I put the TBI on but since I doused it it's trashed. It also has a bit of a hunting idle, like it's going to stall and then jumps back up before leveling out again. It's always done this though even when it was carbureted.

Thanks much...



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[Lumpy Grits]

Well DANG-Look who show'd up.
Thought you drowned in all the rain we had.
Splain yourself-"I put the TBI on but since I doused it it's trashed".
IF you are taking about the main 'puter for the TBI. Send it to Howell for testing.
That 'hunting idle' and surge sounds more like to much fuel than lack of.
LG

 

[Torxhead]

If your fuel return line has any resistance in it that can cause the fuel mixture to increase and run rich. If the 02 sensor goes bad that is another source. To check that sensor you can use a digitial multimeter and watch for the voltage output to go up and down from .1 to .9 volts. When the idle is not consistant, that could indicate a bad iac. The Team Rush upgrade does have a few openings that will allow water and other contaminents to get in which should be wiped out with wd-40. I am sure you have checked all of these items already though. I think a good mechanic could have fixed your Jeep.

 

[Techlight]

Hey LG...Yeah it's definitely been awhile. I read a bit but I haven't posted on the site in awhile.

When I say doused I mean I was splashing through the puddles and the motor got soaked in water and probably got some water in the intake.

Torx:
I have checked those things and/or were told the were checked. It wont hurt me any to poke around a bit more myself though and relook at some things. I didn't check the return line but it seems a simple enough thing to bypass it into a container and see how it runs.

I did unplug all the electrical connectors the other day and hit them with some electrical cleaner just to rule out any moisture. For some reason I was afraid to spray down into the distributor with the same cleaner.

I will also start calling mechanics in the area and see if anyone is experienced with the Howell system. I totally agree that a good mechanic could have fixed the Jeep...I guess the problem is finding one.

 

[Torxhead]

I am surprised that you do not get a code 45 which is the rich condition. If the oxygen sensor voltage is above .7 volts for more than 1 minute, it will trigger the cel. On that return fuel line, Howell states that the oem 1/4" return is sufficient, I have heard of guys going all the way to 3/8", I converted to 5/16". Too much fuel pressure will make it run rich, something could have gone haywire with the fuel pressure regulator which should have been preset to around 10-12 p.s.i.

 

[Posi]

Code 12 means the ecm diagnostics is working as they should.
Is your FI system running open or closed loop?
Give us more info on the 5 day stay at the mechanic shop and the Howell conversations.

I believe your Howell system is working as it should and your problem may be elsewhere.

 

[Torxhead]

You could look down into the throttle body while it is running to check for a dripping injector, if so you could just unplug it. If you do not notice any dripping, you can still unplug one of the injectors to lean out the fuel mixture to make it run better. To get a closer look at the fuel spray, you can point a timing light down the throttle body while it is running. If that fuel return line is still a suspect, you could hook up a pressure gauge to it, Howell states you should get no more than 6 p.s.i. for that. I think that is too much as it only goes back into a vented tank.

 

[Posi]

I took it to a reputable mechanic in my area and they had if for 5 days and were back and forth on the phone with Howell and they ended up giving it back to me because they couldn't figure it out.

They checked: TPS, MAP, O2, IAC, timing, dist play, back pressure, engine temp, fuel pressure. All supposedly good, but it's still throwing code 12.

Seems a reputable mechanic would have figured it out. You mentioned the mechanic checked the fuel pressure, what was it?
I'm assuming they went back and forth with Troy from Howell and after he had the mechanic do some tests he told the mechanic what I previously posted below. This is most likely why he gave it back to you.

I believe your Howell system is working as it should and your problem may be elsewhere.

I suggest you make or buy a ALDL interface cable to receive a live feed to a laptop on the engine's condition. I spent $8 on resistors, a transistor, and DB9 parts, or you can find then for $50-$70 on the net. The program is free online.
Your throttle body has an adjustable fuel regulator as well.

 

[Techlight]

Sorry I went MIA there for a few. I'm swamped at work and personal life right now. Additionally, I can't post from my personal computer for some reason...only the tapatalk app. I tried two different browsers too, so who knows. Maybe I need to update or something.

So, I pulled into grab a few parts and the rear drive shaft bolts at the differential had come loose. Sheered two of them and spit the driveshaft. Fun times for sure. I towed it home, borrowed a car the next day, and then took off work to go buy a car. I've changed that driveshaft a few times and never had trouble with it...apparently I didn't do such a good job about 4 months ago when I changed it or who knows??? Usually I pay good attn when I do that type of stuff. Luckily I was doing like 1 mph when it went.

So I have yet to mess with the Jeep again. It is throwing codes...I was reading the blinking light wrong. Go figure. I'll have to update at another time when I can get under the Jeep. I'll post here again because I know I'm going to need the help when I start working on it again. Will probably be in the next month or so.

Thanks for all the help


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[Lumpy Grits]

Sorry to hear this. Hope the pinion yoke wasn't damaged.
LG

 

[Techlight]

Hey All...So I'm back at this. Sorry to update the thread with a slightly different problem, but this thread has all the history in it. Thanks for bearing with me.

Fixed the drive shaft and all that's fine.

As to the TBI: For some reason it had no codes even though before it was throwing 21 and 33.

So I warmed it up and went for a drive. It seemed to be running ok (none of the bogging down like before). As soon as I got out of the drive check engine light came on. It was throwing codes 21 and 45. I changed the TPS (because mechanic put my old one back on that was showing wide open throttle) and code 21 is now gone but Im now working on the 45 code. Because I had one here I put in a new O2 sensor just to rule that out but I’m still getting the 45 code.



The 45 code page in the Howell manual says I should ground the diagnostic terminal to enable field service mode and run warm engine at 1200-1800 RPM's for one minute and note the service engine soon light.

When I do this it indicates "closed loop" (flashing once per second). At this point the manual says "Code is intermittent. If no additional codes were stored refer to facing page "diagnostic Aids" for possible cause of code 45. If all are ok, refer to ECM intermittent codes or performance in section 2."

Now maybe it's just me but I cant find "diagnostic aids" or the "ecm intermittent codes/performance section" in my howell manual. Anyone have some page numbers if I'm completely missing it. Or links to trouble shoot etc.



Anyone feel like chiming in on next steps and what to be looking for on the 45 code?





For thorough history’s sake: As to what the mechanic noted when I originally took it to them:
codes were 21, 33. They replaced the TPS because it was stuck at wide open throttle. At this point the test drove it and said it was fine. That's when the called me to get it and I drove it and it was running like . Next notes are (bear with me as I try to read the guys writing)

Ignition timing at 8 degrees TDC
Engine vacuum at 14 in at idle, drops to 11 when ECM leans out
Checked play in distributor: minimal 4.5 (might say -4.5)
Have sprayed intake for leaks, none found
"knock indicator" on scanner, cannot locate knock sensor (the kit doesn't have one)
Eng Temp 190-205
Removed 02 and checked for back pressure issue, no change



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[Torxhead]

Code 45 is a rich exhaust condition, so your spark plugs or exhaust pipe should show that. Too much fuel pressure, a clogged up fuel return line, bad coolant sensor, and a bad map sensor amongst a few other possibilities can trip that light. On the t.b.i. between the fuel inlet and outlet, there is an adjustment screw for the fuel pressure regulator with Limited adjustment. I set mine on the low side about 10-11 p.s.i.
This might help:http://www.73-87chevytrucks.com/techinfo/TroubleshootingTBISystems.pdf