Discovery I Talk about the Land Rover Discovery Series I within.

De-computerize

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Old 07-18-2017, 06:00 PM
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Default De-computerize

Ok guy so fed up! One min run good then back to high idle then doesn't want to run right! So the question is can a discovery 1 be de-computerized? We did this to an early 90's jeep wrangler they called it nutter by pass. That ran great got better fuel mileage. So can this happen easy enough or possible.
 
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Old 07-18-2017, 10:42 PM
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does it run well other than the idle issue ?
 
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Old 07-18-2017, 11:19 PM
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that had to be a 1990 or older Jeep, and those were carbureted with a computer that controls the timing, fuel mixture, and idle speed

a 1991 or newer fuel injected inline 6 Jeep runs exponentially better than the 258 ever did, and the reason yours ran better after the change is because something was defective.

That bypass keeps it from changing any of the values and reverts it to a non computer controlled ignition

95 and older Discovery doesnt have computer controlled ignition, and the 96 and newer has as good of a fuel management system as anything else out there. You just have to occasionally change things that stop working after 20 years, which isn't much other than the wiring to the crankshaft sensor and the o2 sensors every 60k to 100k
 
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Old 07-19-2017, 05:26 AM
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Ya her jeep was 91 with with the electric soliod. I have changed every sensor and that wiring for crank sensor. Still have high idle 1500-2000 when cold little lower when warm. But after the rover sits after warm up and come back out from store and it doesn't want to start up. It spits and sputter until you get it above 3k rpm.
 
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Old 07-19-2017, 10:11 AM
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It's hard to say what you've done to resolve the problem, but obviously you've tried hard to track it down and overlooked something in the process, and you are at witts-end. I feel for ya. I've been there a few times myself. All I can say is we're here to try to help you keep the energy up and provide ideas to track it down. How about giving it another go? You have to ask yourself, if you found the problem next week and that completely resolved the problem, and it ran like a million bucks again, would you still be thinking about converting it to non-ECM? So, we just have to help you retrace what you've done and continue to provide ideas to figure out what has been overlooked. How about you start a new thread and outline the steps you've taken so far and we can help identify what gaps might have been overlooked or new ideas?

I bought a real nice 03 Jeep G/C (Overland Off-Road Edition) several years ago used. It looked great, previous owner took great care of it. It ran ok, but had high idle, then unstable idle, would sometimes run like crap and at other times run fine again, then the transmission would shift all over the place, sort of like it had a mind of it's own. The previous owner gave up on it and just wanted to get rid of it (they were taking it to some flunkie mechanic). The Jeep Forum is great and very active but a lot of conflicting ideas on what I was experiencing and I wasn't having any luck for a while finding the problem. I was becoming very frustrated and Pi$$ed off, let alone was very busy at work at the time. Eventually I had to start at square one on my own and plow through. Eventually I found a massive leak on the EGR pipes hidden behind the engine that you couldn't even see or hardly touch (the previous mechanic tried to fix the hole with black electrical tape!!), That $18 part fixed much of the problems, but not all. The TPS was intermittent, IAC gummed up, one bad ignition coil and another one that was intermittent. Plugs no good, Engine not grounded properly (so the ECM may not be getting a good ground connection). The tranny really had me miffed and I though might be really serious. I took to the dealer since my scanner couldn't read, there are a few possible sensors ...and I had to have some warranty work done anyway. They found and replaced a trans sensor for about $140 including labor. It didn't take that long to track these things down once I started digging into it. Since then, and for several years it's run flawlessly for 30k miles. It's been a fantastic rig and a treat to drive! I would say anyone looking for a great off-roader and driver, look at the 04 and down Overlands!! They don't have the L/R charm, but are engineered a whole lot better and have front/center/rear locking diffs. .....anyway I digress....

I have a buddy, OTOH, who basically has spent an amazing amount of hours de-computerizing a couple cars. He says they run great, yet when I've seen them, and ridden in them, they run like crap, smell like crap and 1/2 of the stuff doesn't even work, they have carb lag. Terrible, and to be honest, not all that safe either! And it costs him a lot of time to track down all the stuff he needs, carb, distributor, a bunch of other stuff. I'm thinking, "Wow, this is a step up??" If he'd have put half of the amount of energy into learning how to work with computer controlled cars/trucks, or just paid someone to fix the original problems, he'd have had a better running vehicle and a LOT more time to do the mods and stuff he wanted to do. And more money in his pocket! As a side note, he recently went and bought a pretty nice used snap-on scanner and told me he needs to learn how to work on computer controlled cars.

I guess I'm saying, how about giving another go at it and let us help you get over this situation so she runs like a top again before going down the road of 250 hours of work and a bunch of money to straighten out stuff. You'd be better off buying a different L/R that ran better.

I have a couple carb'd cars, classic cars ...nice cars. My brother has several nicely restored older Mustangs and some other non-Mustang cars, Muscle Cars. These aren't crappy barn projects, driveway beaters or low-buck projects ...they're very very nice restored cars you take to car shows. The engines, carbs, distributors have all been gone through and/or replaced. So I know intimately what it's like to drive those older carb'd cars. But every time I drive those older cars it reminds me how much better computer-controlled cars run and drive. There's just no comparison. That's why Resto-mod cars, where they put modern engines in older corvettes, camaros, Mustangs and such have been the hot ticket for the last 10 years. Actually, the hot trend nowadays is adding computer-controlled retrofit kits from Holley or Eidelbrock or FAST to classic cars. They are throttle bodies that more or less resemble carburetors and all the sensors and ECM in an easy to assemble and affordable kit that doesn't take away the 'look' of a classic car (under the hood) and easily converts older classic cars to essentially computer controlled where they just run better. Just go to Summit Racing site and you'll see what I mean. I know a few guys who've done it and they say it's great. If anything, maybe that route makes more sense for you ...but then you might as well fix what you've got first since you already have all that stuff in place..

EDIT: Oh, I see your other thread about what you've done and such. Obviously a lot. I remember it now. Let me read through and see if I can come up with some other ideas (on that thread) to help out...
 

Last edited by Mark G; 07-19-2017 at 11:45 AM.
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Old 07-26-2017, 01:23 PM
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The short answer is yes, you can do it.

Depending on the year of your D1 you'll need to acquire an intake manifold suitable for a carb, front cover with the spot for the distributor, swap out the camshaft with one that will run the distributor, as well as some other parts I'm forgetting about...

A bit pricey if you don't already have those parts...

My vote is to go for it and rip out those pesky computer components.
 
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Old 07-29-2017, 02:35 PM
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Ok guy I have gone through everything again found nothing. I got fed up so order new ( maf, tps, iac, fuel temp, air intake temp, engine coolant temp, intake vacuum hoses, coil pack, plugs, wires, fuel filter, air filter ) still have high idle actually its higher now 2500rpm. I turn on ac and it will lower to 1500-1800rpm. It still spits and sputter after warm start up but doesn't stall out so far. No check engine lights. I don't have any place in my area to flash computer to reset only have rover dealer 2hr in each direction and way to expensive. Any ideas?
 
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Old 07-29-2017, 04:43 PM
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Couple ideas:

1) No codes, huh?

2) Did you read the recent thread about the computer case getting water in them and corroding contacts inside the computer? I'd have a look inside if you haven't already. There were some people really scratching their heads until others suggested that.

3) Do you have an Ultra gauge or diagnostic device so you can view what signals (from the various sensors) the computer is ACTUALLY reading? A person can replace sensors but if there are burnt wires, corroded connectors or things like that....

4) I believe I read a thread recently about a module behind the cluster which affects idle too??
 

Last edited by Mark G; 07-29-2017 at 04:51 PM.
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Old 07-29-2017, 07:52 PM
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Originally Posted by Mark G View Post
Couple ideas:

1) No codes, huh?

2) Did you read the recent thread about the computer case getting water in them and corroding contacts inside the computer? I'd have a look inside if you haven't already. There were some people really scratching their heads until others suggested that.

3) Do you have an Ultra gauge or diagnostic device so you can view what signals (from the various sensors) the computer is ACTUALLY reading? A person can replace sensors but if there are burnt wires, corroded connectors or things like that....

4) I believe I read a thread recently about a module behind the cluster which affects idle too??

I have ob2 scanner and it has a live view and the tps is reading 12.5 when truck off. Some of the other sensor I don't know what the info should be. But the tps is not right I do know. I haven't taken computer apart to see about corrosion. And I'd like to know more about this module?
 
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Old 07-29-2017, 10:36 PM
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Have you read through this post:
https://landroverforums.com/forum/di...gh-idle-32201/

Couple other things:
If you unplug your IAC when it's running, does the idle drop?

Did you thoroughly check all the vac hoses, possibly put a vacuum gauge on it to read what it says. Maybe take a propane torch with a length of hose on it, crack the valve and move the hose closely around different parts of the top of the engine while it's running to see if it changes the idle (a vacuum leak)?

Have you check your PCV valve (Assuming it has one). Make sure it's working.

Dumb idea, but I had a rodent once deposit an acorn on top the intake which fell down under the throttle stop above the manifold causing a really high idle. The way the intake is designed, it's like a funnel and if a rock or anything were to get thrown up into the general area, it would get funneled down and wedge down at the throttle stop preventing the pedal from fully retracting. Worth checking if you haven't.

Check the vehicle speed sensor? (Per the link above)

I'll see if I can find the thread about the module behind the cluster.
 

Last edited by Mark G; 07-29-2017 at 10:42 PM.

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