rebuilt 2.9 dies in closed loop...help!

[mhavoc]

Hi experts...

I have had my 1986 Ranger 2.9 for about 10 years now and finally bit the bullet to have the entire engine rebuilt rather than trying to hack it together. I used Kunz's excellent info as a roadmap as I bring this baby back to it's full glory. Anyway, now to the problem I am having.

In a nutshell, starts right up... runs great, actually purrs, you can hear it's pleasure after being completely rebuilt. Revs nice, doesn't seem to miss. UNTIL.. it hits operating temp (the mystical ~145 seconds) and the ECM switches to closed loop, then the engine starts to sputter and after about 3 seconds it stalls. From the exhaust there is massive gas odor so it seems like it is flooding itself out (more later on this). It will start right back up if I floor the gas pedal, but if it is already at temp, then after exactly 4 seconds, the missing followed by a stall happens again.

On the road, it is remarkably similar. I can drive around but after about 4 seconds, it starts to miss and I basically need to floor it (full throttle should put it back in open loop right?) and it will muster itself out of the stall rev fully and run great. If I keep the throttle pegged, it is fine, however, can't zoom around northern colorado with my gas pedal at the floor all the time. If back off of full throttle, after 4 seconds, the engine again, starts missing, then will stall after 3 more seconds if I don't floor it again to temporarily snap it into open loop.

I drove 60 miles home tonight and I got about 10 miles per gallon with all the revving every 5 seconds, so again, seems like it is running *way* rich? Also, I notice that even when I have it at full throttle, it will still miss every now and again and isn't really running perfectly smooth yet.

Some history...

1. In addition to the new engine rebuild, it has new 19lb injectors, new coil, new wires, new distributor and plugs. Timing @ 12 degrees.
2. After the engine was rebuilt and installed it didn't really run well at all. The O2 sensor connector seemed to have melted at some point so this was deemed to be the problem and the O2 sensor replaced and the connector fixed. Seemed to be a little better, but not very good at idle still.
3. Checked engine codes, nada. Seemed rich so we check the fuel pressure to see if it was wacky... seemed normal at 35psi.
4. Thought the old 'Ignition Control Module' on the distributor might be the problem so we replaced it. No change.
5. Got a random TPS range code, so we replaced that, seemed to make it run better at idle.
6. Based upon posts here I checked the Idle Air Control (IAC), cleaned it out, linkage seems to be nice and smooth now. Didn't make any difference however.
7. Thought maybe the 'Ignition Control Module' we got was bad, so we put in another one just in case... no change.
8. The engine did this *before* it was rebuilt too, so there is something definitely lingering as a problem in the ignition system.

My next thoughts and actual questions...

1. I figure with the rich mixture the the 'new' O2 sensor might be fouled at this point? Do you think it might be worthwhile to try another one?
2. My harness sucks, the connectors on the driver side fender are a mess, but I have checked all the connections and everything seems okay. I really should just buy new connectors and re-solder nice pins on each wire since I am an electronics person (computers not cars. ). Any suggestions on whether I should just get a new harness or try and 'fix' this old one?
3. What else could be the problem? Im going to pull the ECM tomorrow and make sure the connector pins aren't oxidized etc. Beyond that, Im at the point of just going to a MAF system?
4. I attached a photo of a mystery wire on my harness... it is coming from the driver's side firewall and has 12V on it when ignition is on so it must go somewhere since it isn't insulated. perhaps the insulator just fell off tho? The size of the female connector does not allow it to fit into any of the plastic connectors, so it doesn't belong in any of them as far as I can tell. It is Green with a Yellow stripe.

If anyone has any thoughts or suggestions, I would be very grateful. Im going to pull this baby into my garage tomorrow and fiddle with it every night until it runs the way it should. DOH!!

thanks

jess

 

[Psychopete]

I've run 19lbs injectors on a 2.9L w/ a cam and MAF computer before using an IST mass air adjuster to fool the computer, but never tried on a stock system as it set. Are you sure you installed 19lbs? They are the wrong ones. But I am not familiar with enough on what would happen, but just a heads up that they came w/ 14lbs injectors from Ford, and that the computer is programmed in for driving injectors of that size. Did you get no codes, or the pass 11 code?

 

[mhavoc]

19lb injectors vs stock...

Hi PsychoPete...

thanks for the response... I was wondering the same thing at one point but from what I read (like here http://www.therangerstation.com/tech_library/2_9_Page.html), it doesn't really say that the MAF conversion is *required* for the 19lb injectors, it simply has the injectors upgrade listed as a 'tip' in itself. At least that is they way I am reading it. I have my old injectors still. Also, Im getting no codes from the computer at all.

Im curious about my LiteGreen/Yellow currently. Looking at the wiring diagram last night since that is the color of the EngineCoolantTemperature sensor, I will see if it is one in the same or if it is a LiteGreen/Yellow wire for something else.

Also, I checked the Fuel Pressure Regulator for leaks into the vacuum line, no fuel there.

 

[Psychopete]

G/Y is usually the coil ground, but I'll have to check my EVTM later when I get home, not sure if I'll have time to get to it tonight though.

I don't know why that's listed in the technical library as an upgrade, that information is incorrect for a bone stock engine as a performance upgrade. The stock injectors are completely sufficient for the engine, and would never peg out to justify needing anything else. If you ran boost though where you're forcing more air into the cylinder, at that point you would need the higher flowing injectors.

 

[mhavoc]

Looks like the coil ground is DarkGreen/Yellow, whereas this one is LightGreen/Yellow. Looking at the wiring diagram this might just be an unused wire from the 2.0 Idle Speed Control perhaps.

I put my original 14lb injectors back in tonight but can't take it for a test drive until tomorrow evening. I will report back on what happens.

 

[mhavoc]

solved

Just to wrap this one up... while there are still a few issues... it looks like my major problem was the 19lb injectors rather than the 14lb stock ones. In hindsight, this makes perfect sense since the larger injectors aren't what the computer is expecting. I guess in my quickness to get parts ordered, I took the 2.9 FAQ a little too literally in 'upgrading' to 19lb injectors.

The other oddity was the LightGreen/Yellow mystery wire. Since this went through the drivers side firewall, I looked a little closer to the wiring diagram and I did find a LTG/Y wire that was used for the Idle Speed Control on the 2.0l engine. That makes sense since that wiring would have sat on the driver's side fender (I think)... The wire I thought it was, the Engine Temperature Sensor for the ECU, goes through the passenger side firewall.

thanks for the help!!!

 

[gaz]

Closed loop problems

"mhavoc",

The only time I ever had closed loop problems is when I was supplying way too much air for the engine to use. It interpeted the condition as a "start-up" condition and stayed in the cold engine condition. This killed my fuel economy and forced me to learn exactly how much air to let the engine have, verses, giving it as much as possible.

I don't think this completely pertains to your situation but... in case it could help.

Kevin

 

[fordfan]

I know this is old, but thanks guys! I have been wondering if I could do a 19lb swap in my rebuilt 2.9L without mods as listed on 'tips' also! It's been hours of searching for the answer, but I finally found it here-thanks for saving me lots of trouble!!

 

[okietheranger]

There is a I belive tan single wire that useally bolts to one of the top tranny bell housing bolts it needs to be grounded. Check that wire. My ranger did the same crap with that single wire off. Hope that helps

 

[okietheranger]

Oops I see u already got it fixed