OPen loop stall, or at least I think it is open loop!

[Neo]

I searched the forum to no avail. Here is the issue, I figured you guys/gals have seen it and fixed it previously...
WHen cold (isn't this open loop?) the engine does not deliver much torque. Everything (at least that I can think of) is right in terms of mechanics (compression etc). THis only is noticable at cold start and most of the time right after start. Today, as has happend on other very cold (SIC) mornings, the car stalled as I was backing out of the drive, leaving it dead in the middle of the road. It would not start again. It would crack, and every so often act as though it was going to fire, only to continue to crack without fire. spark is present, just won't start. I believe it is flooded due to the ECU calling for heavy fuel in open loop mode. Once it is warm, it never does this. Today is one of the colder mornings we have had all year and it was very apparent. Is there anything I can do to remedy this? I have a MSD off-road 6 I took out of my YJ and was wondering if that would help? Any suggestions are greatly appreciated.

Jeff

[robisonservice]

I suggest you connect a scan tool with live data and look at the signal from the mass air meter, and the temperatuer sensor readings. I think you'll find one of them is significantly off.

[Roadsiderob]

Back in 1994/1995 when the cars were new we had cold start issues. Land Rover issued a bulletin outlining several updates and things to check. I would make sure it has had the updated PROM chip. There were cold start issues when new...ECU overfuelling to light off the cats quicker...PROMs were updated to new tune, but yours may not have been done if the truck was in a warm climate. Also in 1995, the IACV castings were miscast/mismachined and the air passage to the IACV was too small...there was a "fix" to take it off and file the opening to the correct size. Cranking speed is very important to get the truck started before it floods. Make sure your battery is in top shape...I believe that is when they spec'd the NAS D90 to the diesel size battery. That is also when they introduced the larger KW Bosch starter. I think they also had us replacing the push on coil connectors with ring terminals to bolt them down solid.
If your truck is flooded, locate the EFI trigger wire that comes across the valve cover and plugs into the negative side of the coil. Remove the wire from the coil. This will turn off the fuel. Hold the throttle wide open and crank the engine over. It will probably start, sputter and die. This will clear your flood condition. Reconnect the trigger wire and try and restart the truck.

[Neo]

Thanks guys, great information. I will try the negative ground disconnect next opportunity. Not certain where I could (other than the stealer) get someone to check the codes, nothing was showing on the digital display on the ECU. ANy ideas on how I can check for the code updates? I will check the IACV opening, but not certain what it should be. I'll search the site and check the tech areas. In the event the code/maps need to be changed, cause the car has been in the SE all its life, where or who would re-flash the PROM? I have seen posts sometime back about a new PROM, are they still available? THanks again oh Great D-90 Gurus!!

Follow-up Post:

Dead on Rob! Hit it right on the head. I was pretty confident it was flooding just from the way it died and when it died. Went home at lunch and pulled the fuel injector ground lead from the coil and she fired right up, then died exactly as you said. Put it back on and she started right up and drove into work. I am going to pull the Inlet Air valve and would liek to know how large I should file this opening. Also, I remain very interested in the ECU PROM, and where I might find one with the correct mappings. Thanks again!!

[Andrew Vick]

So would the above indicate a bad coolant temp sensor, as John alludes to? I've got the same thing going on and a mechanic who is trying to rip me.

[Roadsiderob]

If there is nothing on the digital display, there are no codes in the computer. The PROM in this case is an actual computer chip that you will have to replace. It plugs into a socket on the circuit board. I think the original tune was like a 3361 maybe and the new tune is like a 3365...the part number is like PRM3365 or something...the parts dept. should be able to look it up for you. If you take the IACV housing off of the plenum (3 allen head bolts) and look at it, the air passageway that leads into the chamber where the IACV screws in should be about 11mm square. Some in 1995 were miscast and are about 7mm. This can be a problem. the solution was to file it out to the proper dimension.

[Andrew Vick]

Thanks Rob! I'll keep the board posted. This has also always been a southern vehicle, so it probably never got the prom.

[Heath]

Check the "thermistor" (engine temperature sensor). The connector for it looks like a fuel injector looking connection on the front of the intake manifold (If I remember correctly). This will cause a poor cold start (no choke -- to put it crudley).
This would usually throw a code, but make sure it is connected properly and working (not connected to a fuel injector-- I had this done once after installing an engine too quickly) :embarress
-Heath

[Andrew Vick]

Now I've got an intermittant no start, usually when warm (engine has been running). Smells flooded, and if I wait a few minutes, it will start with the throttle floored. Will always restart floored or when cold (-15 to 40). I have changed the coil, amp, plugs, cap, and rotor. I've also tried another ECM with the same results.

Put old ECM back in and it seems to be working, but we'll see this week. I'm wondering if it's a fuel problem, like bad gas, but that doesn't explain the warm no start/flood smell.

Any ideas?

Follow-up Post:

Now I've got an intermittant no start, usually when warm (engine has been running). Smells flooded, and if I wait a few minutes, it will start with the throttle floored. Will always restart floored or when cold (-15 to 40). I have changed the coil, amp, plugs, cap, and rotor. I've also tried another ECM with the same results.

Put old ECM back in and it seems to be working, but we'll see this week. I'm wondering if it's a fuel problem, like bad gas, but that doesn't explain the warm no start/flood smell.

Any ideas?

[Scott 9835]

Fuel pump or relay?

[geoellis]

The PROM in this case is an actual computer chip that you will have to replace. It plugs into a socket on the circuit board. I think the original tune was like a 3361 maybe and the new tune is like a 3365...the part number is like PRM3365 or something...the parts dept. should be able to look it up for you.

Resurrectng this thread because I have a buddy who needs this chip. Anyone have one or know where to source one?

Thanks.

[Mowabb2]

Thanks for the help. Hopefully someone will point us in the right direction.

G

[rover4x4]

Maybe try a new ECU, there were some for sale here recently

[geoellis]

How can you be sure that a new ECU won't have the same issue? Seems that the PROM is what corrected the coding in the ECU.

[rijosho]

I have one of these.

http://www.d-90.com/forum/showthread.php?t=27879

[pendy]

Nowadays as the trucks are many years older, you need to rule out bad injectors before worrying about the Fuel ECU PROM.

I may have a few of the cold start PROMs around still. But they will not do much good if the injecotrs are pouring to much fuel in due to age and wear.

You might search fuel injecors here for a while and try to diagnose the problem on the vehicle some more.

[rover4x4]

I have a set of those ford injectors that got such high marks, my oil smells like fuel after a few hundred miles. I don't think its the injectors, I have been trying to kill this truck for 10k and it wont quit.

[Turbofan]

You might try a engine speed sensor. I've seen many of these things act this way as they slowly die. However if you aren't loosing an injector signal or spark, your problem is elsewhere. If you can get it to act this way regularly, have one of your buddies with an Autologics look at the engine data while it cranks.

[geoellis]

Thanks for the suggestions everyone. The good news is that his mechanic found the chip, so that should solve the issue.