'89 RRC: The engine (finally, after 14 months of tinkering) warm-starts and ticks over like a dream, but she experiences a stall at one single point in the rev range...
I can pull away from stationary and get to about seventy-ish with a lovely, smooth, uninterupted power curve, but when I hit that speed the engine stalls. By either pressing down further or letting up a little I can instantly resume normal service, but the speed limit in Nevada is 75mph and that's exactly where this gremlin lives. Exactly! So I can't use my cruise control (which - yes - I have managed to get working!!!).
Amongst all the many and varied gubbins I've replaced on the engine, be aware that I've fitted a replacement used-but-good MAF sensor (no effect) and a new after-market hose between said sensor and the EFI's plenum chamber (no effect). What the hell else can it be?
Other symptoms: Despite my best efforts, I only get about 10mpg on a good day, and she hates to start in the cold, coughing and spluttering and refusing to go above 25mph for a mile or three until she warms up. And oh she is slow from a standing start - far slower than a V8 3.9 should be.
Don't think I have O2 sensors, because I had the cats removed and straight pipes welded in their place.
However... the other gubbins... is there a site anyone recommends for good prices and services. I mean, I'll do the research myself if I need to, but if there's one supplier who's everyone's favorite, I should just go there.
These problems always seem to come down to the TPS. Also, I'm not sure about your '89, but my '93 has both O2's pre-cats. I would imagine you'd have more problems then you currently do if you were running with no O2 sensors without some modification to your ECU - assuming there is a mod to do for such. Expensive little pain in the ass - TPS is probable.
Okay, you're right, I do still have both O2 sensors:
But as you can see they're damn close to the welds where the cats were removed. Does anyone think the extreme heat from the welding could've / would've damaged them, even though they are designed to live in such a high-temp environment?
And if some-one on the forum has an oldie-but-goodie used TPS, please let me know before I go emailing dealers or buying a new one.
Same problem with my 1994 RRC - Misfire at 2,000 RPM (or 70mph).
I have replaced the following in the last month:
TPS ($210!!!), the Idle Air Control Valve ($38), New Coil, Cap, Rotor (all Lucas), NGK Plugs, 7mm plug wires, vaccum lines...and cleaned the MAF sensor, throttle body and the K&N air filter.
...and STILL the damn thing misfires at 2,000 rpm. I have isolated it to RPM and not speed (15 mph in first gear at 2,000 rpm is same misfire / hitch as top gear at 70mph). So I have ruled out the trans and the torque converter lock up.
What the hell else could it be?!?!?! HELP!!!!
No fault codes on the display and no dash lights on.
No indication this problem even exists and I cannot diagnose it (yet).
I have spent about 6 hours on this forum looking for the fix...not there yet.
Could it be: Ignition amplifier? Alternator? Fuel pump? Distributor? Pure Evil?
Do not replace your $200 TPS until you are damn sure that is what is is.
I didn't and now I have an extra $200 TPS in my glove box, right next to my extra IACV.
Please Help Us O Wise Ones!
__________________
Road rage would cease to exist if everyone drove a 109" 2.25L diesel.
Same problem with my 1994 RRC - Misfire at 2,000 RPM (or 70mph).
I have replaced the following in the last month:
TPS ($210!!!), the Idle Air Control Valve ($38), New Coil, Cap, Rotor (all Lucas), NGK Plugs, 7mm plug wires, vaccum lines...and cleaned the MAF sensor, throttle body and the K&N air filter.
...and STILL the damn thing misfires at 2,000 rpm. I have isolated it to RPM and not speed (15 mph in first gear at 2,000 rpm is same misfire / hitch as top gear at 70mph). So I have ruled out the trans and the torque converter lock up.
What the hell else could it be?!?!?! HELP!!!!
Have you checked your timing and both mechanical & vacuum advances?
Quote:
Originally Posted by RogueSeriesIII
Do not replace your $200 TPS until you are damn sure that is what is is.
I didn't and now I have an extra $200 TPS in my glove box, right next to my extra IACV.
I have not yet flashed my timing light on the situation.
It does kinda feel like a timing advance issue (always at 2K rpm).
I replaced the vacuum line, but will check the timing next.
Do you know the timing specs? (at idle and at 2k rpm)
Both vaccum and mechanical advance? How do you check each?
How do you test the TPS? Voltmeter?
Keep the help coming...much appreciated!
__________________
Road rage would cease to exist if everyone drove a 109" 2.25L diesel.
Do you know the timing specs? (at idle and at 2k rpm)
Both vaccum and mechanical advance? How do you check each?
How do you test the TPS? Voltmeter?
Timing is 6º +/- 1 BTDC (some advance it to 8 or 10, whatever feels right)
Should be checked at idle with the vacuum advance disconnected.
I don't know what it should be at 2k rpm. You can check the mech advance by seeing if the rotor rotates a few degrees & springs back to original position.
You can check the vacuum advance with a vacuum pump to make sure its holding. Not sure how much though.
Here's for the TPS. You can probe at the connector too. The wire colors are escaping me at the moment. Have a look here... RPi Engineering - V8 Engines
There are cheaper options for the IACV (stepper). Do a search here or at rangerover.net for more info. I think I using one for an Astro van. Sorry I do not have the part #.
Ooookay then... perhaps the world's dumbest question... in testing this damned TPS...
The link you gave offers different ideals for cat and non-cat models. So... mine was manufactured with cats, but doesn't have them any longer. So am I aiming at the cat or non-cat ideal figure?
Sorry if this is unspeakably dumb, but I have to ask!
Ooookay then... perhaps the world's dumbest question... in testing this damned TPS...
The link you gave offers different ideals for cat and non-cat models. So... mine was manufactured with cats, but doesn't have them any longer. So am I aiming at the cat or non-cat ideal figure?
Sorry if this is unspeakably dumb, but I have to ask!
The model differences is referring to the MAF settings. The lower the voltage the leaner the fuel ratio. IIRC mine is set at 1.5 with cats.
In testing the TPS, you're looking more for the second test from the WSM. You will most likely find a flat spot in the scaling which is why you loose power.
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Hiccup on Acceleration Curve
Linear Mode
