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1970-1995 Range Rover Classic
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Discussion Starter #1
First off let me thank you guys, you've been an unbelievable source of advice on my trucks over the years. I'm kind of stumped on this issue on my 88 and look forward to your feedback.

1988 with 110K. Truck starts up, although takes some time to finally kick over. Idles 95% perfect, slightest little stumble but idles all day at 600 RPM. Doesn't overheat or run hot. New O2 sensors, coil, dist. leads and rotor arm. New fuel pump and filter. Every sensor new with the exception of the TPS. (had a larger budget and was trying to be proactive with the age/mileage).
Runs beautifully, until it really warms up. Usually happens after driving anywhere from 10-15 minutes in stop and go traffic or 10-25 miles highway. All of a sudden you'll smell a burning smell, and it'll have a super hot sooty exhaust, audible misfire and you can tell it is running super rich. starts to idle at less than 250-300 RPM. I have an ignition amplifier relocation kit on the way, the current amp looks older. Is this the most likely problem? As soon as it sits for a while and cools down, it starts up and idles perfect again. Any advice and help would be greatly appreciated!
 

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1970-1995 Range Rover Classic
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220 Posts
First, I would swap the old coil back in and see if it behaves the same. Additionally, I would test the new OS sensors to determine if they are functioning properly.

Also, have you replaced the ECU temp sensor?
 

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Something to check that was sorted about 3 pages back under "3.9 hot start problems" the number one cylinder injector plug had been confused with the manifold temperature sensor with the plugs being fitted transposed. The symptoms seem very similar to your description.

It gives the ecu a false temp read resulting in odd mixture variations.
 

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1970-1995 Range Rover Classic
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220 Posts
I should have inquired before offering advice - were the new parts installed to address the rich mixture issue? Or, did the issue present following?
 

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Every now and again mine has same thing
Burnt smell
Runs chitty
I put it in nutral
Turn it off
Coast for a bit
Restart
Put in drive and then it runs fine
I think it has to do with the base idle
Check your throttle body and see if the plug has been removed
Mike
 

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1995-2002 Range Rover Classic
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1,413 Posts
an 88 has the old early 14 cu ecu, swap it to a later 14 cux ecu, its a straight swap and the engine runs better.
something else to keep in mind is the 3.5's used to go thru cams. a worn out cam will behave odd as the proper valve lift just is not there.
 

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1970-1995 Range Rover Classic
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Discussion Starter #7
Thanks for the replies! I was thinking of swapping out the ignition coil, I replaced it as a precaution only. The temp sensors were all replaced, even the fuel temp sensor. All of those things were replaced as a precaution only, I didn?t have the issue previously. This has only happened in the last few days. I?ve also been replacing all of the vacuum tubing, there were definitely a few that were rotted, especially the short tubing that goes from the ram housing to the fuel pressure regulator. The other problem is if I let the truck sit and idle, it doesn?t happen. It?ll only happen after driving awhile. Does it sound more ignition related?
 

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Even though the temp sensor has been replaced, check it with a meter and as suggested check the plug did not get swapped with #1 injector.
Check timing too.
Like 95classiclwb said, they do run a bit better with a 14cux as opposed to the 13cu but if you want to rule out the ecu I can loan a 13cu just pay rt shipping.
 

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1970-1995 Range Rover Classic
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Discussion Starter #9
Thanks for the possible ECM loaner. I?ll definitely let you know. I just checked to make sure about the connectors, and we?re in the right spots. What?s the resistance I should see at the sensor? To answer another question a did the base idle reset procedure in RAVE and I did it again using the Rovers North procedure. Also of note: the ignition coil is a cheaper aftermarket, and the MAF is also a cheaper aftermarket, both sourced from an online rover parts vendor
 

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1970-1995 Range Rover Classic
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Discussion Starter #10
All of the new sensors are Britpart and Lucas, with the only exception being the fuel temp sensor, that was purchased as a know good sensor OEM used
 

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1970-1995 Range Rover Classic
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Discussion Starter #14
Base idle..... did you set it with the engine at operating temp?
Good question, I did set it with the engine fully warmed up. The idle seems to go down very low because it’s misfiring so badly. It literally pop/backfires out of the exhaust when it happens. The cats are removed so I don’t know if that makes the sound/smell louder
 

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1995-2002 Range Rover Classic
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you should be using some kind of software such as rover gauge just to see what the 02 sensors are really doing, with out cats it will smell rich even thou it may be running with in stoichiometric.
also check for vacuum leaks, two major sources will be the intake boot if it is the original still (look like its wrapped with a rag), the replacement should be rubber, the other is the brake booster. at nearly 30 yrs of age I'm sure it has an internal leak thus contributing to rough running.
check your timing as well.
 

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1970-1995 Range Rover Classic
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Discussion Starter #16
I checked the booster for leaks, none found. The intake boot seems ok, but I've suspected it for awhile. When it misfires it's definitely not stoichiometric, the tailpipe gets jet black from soot. The exhaust is new, so after the first misfire incident I cleaned out the inside of the pipe to check. Stayed nice and shiny for a week then after the latest incident, it turned black again. It's acting as though it's shutting off at least two spark plugs and flooding the chamber with fuel. Unfortunately I can't use any software based diagnostics because I still have the Lucas 13CUX in the vehicle. /:(
 

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1970-1995 Range Rover Classic
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I checked the booster for leaks, none found. The intake boot seems ok, but I've suspected it for awhile. When it misfires it's definitely not stoichiometric, the tailpipe gets jet black from soot. The exhaust is new, so after the first misfire incident I cleaned out the inside of the pipe to check. Stayed nice and shiny for a week then after the latest incident, it turned black again. It's acting as though it's shutting off at least two spark plugs and flooding the chamber with fuel. Unfortunately I can't use any software based diagnostics because I still have the Lucas 13CUX in the vehicle. /:([/QUOTE

“I was thinking of swapping out the ignition coil, I replaced it as a precaution only. The temp sensors were all replaced, even the fuel temp sensor. All of those things were replaced as a precaution only, I didn’t have the issue previously.”

The issue presented after the parts swap. Typically, this is down to faulty new parts, a connection/wires being disturbed or, a botched install. It could be down to all....


However, It seems ignition related – Again; I would swap back to the old coil first and continue from there.

I would only change one item at a time to eliminate variables.
 

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1995-2002 Range Rover Classic
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the software works with 13 cu system, it is the same plug. I purchased a new cable from this place "[email protected]" it comes with instructions and a CD loaded with the rover gauge software.
the difference between 13 and 14 systems is the upgraded chips, but in all basic functions are the same as far as diagnosis.
 

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1970-1995 Range Rover Classic
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Discussion Starter #19
I agree with your thought on ignition system. I'll swap out the coil tomorrow and report back. I originally swapped out the coil because it was rusty and had that "I'll make you call roadside assistance" look to it. If that ends up fixing the issue, does anyone have a recommendation on which new coil to buy? I keep seeing the MSD Blaster mentioned in various forums. I'd prefer something that I don't have to add any resistors too, etc.
And again, I really can't thank you guys enough for all of your help in this! :thumb:
 

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Discussion Starter #20
the software works with 13 cu system, it is the same plug. I purchased a new cable from this place "[email protected]" it comes with instructions and a CD loaded with the rover gauge software.
the difference between 13 and 14 systems is the upgraded chips, but in all basic functions are the same as far as diagnosis.
I'll check it out! That would be fantastic if I could have something to work with my old system
 
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