ptschram
Well-known member
lforgue8 said:
Ohm out every wire to the ECU! No fun, but guaranteed to either fix it or rule it out.
'95 4.2 w/rough idle when warm...
- Thread starter 57loboy
- Start date
Ohm out every wire to the ECU! No fun, but guaranteed to either fix it or rule it out.
FWIW - I've had the very similar problem in my 95 LWB, that deteriorated to the point where I had to ratchet up the throttle cable so it wouldn't die on my way to San Diego. At the gas station in Pismo Beach, I found the screw holding the vacuum advance unit very loose. Tightened it up and all went away (not quite completely).
The other thing to consider (mentioned here a while ago) is genuine LR stepper motor replacement, rather than generic Chevy unit.
The other thing to consider (mentioned here a while ago) is genuine LR stepper motor replacement, rather than generic Chevy unit.
ptschram
Well-known member
p m said:
The first time my truck got to ride on a tow truck, it was due to both screws falling out of the distributor to the vacuum advance!
Paul don't tell me you didn't have a tube of CrazyGlue around!
(nail polish works, too - but you wouldn't have it around unless you build marine or airborne equipment)
(nail polish works, too - but you wouldn't have it around unless you build marine or airborne equipment)
ptschram
Well-known member
Not yet... Haven't had a chance to do anything with it as one of my other cars (Piece o'crap Ford) decided to eat its water pump this weekend. In doing that, one of the studs snapped off in the timing cover so I've spent the last few evenings trying to get that sucker out. As I'm pulling the timing cover off to get the stud out, I'm now doing a timing gear/chain swap on that. Hope to have all that back together tonight. What a week... As Paul told me the other day "When it rains, it pours..."
57loboy said:
neither did i...i was hoping you found something
.....my shoulder problem showed up sat afternoon and i was supposed to paint my porches at home so that went on the back burner and then i woke up sun morn and threw out my back so i had to spend the day on the couch so i could go to work mon:banghead:ok sooooo.....
truck ran and died.....checked coolant sensor readings where fine....repl with known good sesnor anyway and ran truck.......died again......replaced high resis wire from fuel pump relay to pump....died again.....BUT TRUCK ALWAYS STARTS BACK UP.........let truck run again but this time wont start back up.......chk signal from pickup and no flashing from test light!..........let trcuk cool and then started again......died i rechecked the pickup signal and no flashing of test light.....so i think the sensor inside the pickup assembly goes open when it get hot enough and just like my relay problem closes back when cool allowing me to restart the truck......
I will be ordering a new pickup and installing it in a week or so but i feel good about this one now
my ramble is over how you doing with your truck?
truck ran and died.....checked coolant sensor readings where fine....repl with known good sesnor anyway and ran truck.......died again......replaced high resis wire from fuel pump relay to pump....died again.....BUT TRUCK ALWAYS STARTS BACK UP.........let truck run again but this time wont start back up.......chk signal from pickup and no flashing from test light!..........let trcuk cool and then started again......died i rechecked the pickup signal and no flashing of test light.....so i think the sensor inside the pickup assembly goes open when it get hot enough and just like my relay problem closes back when cool allowing me to restart the truck......
I will be ordering a new pickup and installing it in a week or so but i feel good about this one now
my ramble is over how you doing with your truck?
Maybe I'm off base here but I had a similar problem with my '89. You said in post #1 that you snipped the end of the vacuum hose, put it back on and it was fine for a bit. I did the same thing and a day later the problem was back. So I went and replaced ALL the vacuum lines and that cured it. If you haven't done so already it might be worth trying for $5.
Frank - thanks for the thought - simple can be better sometimes. However, the problem has gotten worse each time I've tried to diagnose it, to the point where now it won't start at all. Unless there's a gaping hole somewhere in the intake, I can't imagine a vacuum line doing this and everything else is new (heads, etc). When I did all that work, lines that were obviously bad were replaced.
Luc - I got the p.o.s. Ford back together last night, runs well after the 152k mile timing chain/gears were swapped out! Hope to have a chance to work on the Rover this weekend, but that is filling up with activities that will make it difficult at best. I'll keep you posted for sure!
Luc - I got the p.o.s. Ford back together last night, runs well after the 152k mile timing chain/gears were swapped out! Hope to have a chance to work on the Rover this weekend, but that is filling up with activities that will make it difficult at best. I'll keep you posted for sure!
Tom,
so it wont start at all now huh.....youve tried to jump the fuel pump relay? have you taken off the access plate and given the pump a good wack with a hammer to see if it starts?
just to be sure chk the interia switch too
good luck and keep me posted
so it wont start at all now huh.....youve tried to jump the fuel pump relay? have you taken off the access plate and given the pump a good wack with a hammer to see if it starts?
just to be sure chk the interia switch too
good luck and keep me posted
I posted earlier in the process that fuel is no issue - 38psi, holds it for almost 24 hours before dropping. spark and such is fine too. As PT indicated - "time for brute force diagnosis". I need to see if the timing chain has left the building by allowing things to get too loose or if the dist or cam is somehow bad. Cam looked good when I did the heads 7k miles ago, we have spark, but apparently not at the right time. I'll do better if I have a second set of hands and my usual go-to Rover mentor has been as busy as me!
ptschram
Well-known member
OK, let's see if we can determine the condition of the timing chain without tearing the front cover off.
Hold on! This is a '95, right? Pshaw! pull that front over off, it's not that bad! You need a front crank seal anyway!
Hold on! This is a '95, right? Pshaw! pull that front over off, it's not that bad! You need a front crank seal anyway!
Take this FWIW, but the last week I've been having trouble with the "new" LWB, '95 4.2. Thing was just running like shit *AFTER* I did the following:
New plugs, new leads, new cap, rotor, timed to spec, replace all vacuum lines, torqued intake manifold bolts (vacuum at 15psi, idle). CHecked coil, okay. Checked MAF, okay, checked coolant temp sensor, okay, checked fuel pressure and pressure regulator, okay, replaced tube from MAF to plenum, cleaned stepper motor, cleaned PCV and associated hoses. Runs like shit, smells rich, stumbles, worse under load.
So my dad says, "Give the distributor a twist". So I hook up the light and advance it about 5 degrees and she starts purring like a kitten. Took it for a test drive, runs like any good 4.2 will run -- fast!
Only thing is, when you start it cold, it revs to about 1500 for about 5 seconds and then ratchets back down to 750 where it doesn't miss a beat.
New plugs, new leads, new cap, rotor, timed to spec, replace all vacuum lines, torqued intake manifold bolts (vacuum at 15psi, idle). CHecked coil, okay. Checked MAF, okay, checked coolant temp sensor, okay, checked fuel pressure and pressure regulator, okay, replaced tube from MAF to plenum, cleaned stepper motor, cleaned PCV and associated hoses. Runs like shit, smells rich, stumbles, worse under load.
So my dad says, "Give the distributor a twist". So I hook up the light and advance it about 5 degrees and she starts purring like a kitten. Took it for a test drive, runs like any good 4.2 will run -- fast!
Only thing is, when you start it cold, it revs to about 1500 for about 5 seconds and then ratchets back down to 750 where it doesn't miss a beat.
Still haven't had a chance to tear into this. Was reading on another board where someone is experiencing the same symptoms I was earlier...how could I best diagnose the condition of the fuel injectors on this in its present condition? I am quite sure they are original...
ptschram
Well-known member
If your fuel pressure is holding with the key off, chances are the injectors are at least not leaking. Doesn't give us any indication as to spray pattern, but we can assume they aren't leaking.
Anything definitive will require removing the injectors and having them flowtested. To be honest, it's almost as expensive around here to do that as it is to replace them. Cleaning and flow testing IS more expensive than just replacing them.
Anything definitive will require removing the injectors and having them flowtested. To be honest, it's almost as expensive around here to do that as it is to replace them. Cleaning and flow testing IS more expensive than just replacing them.