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Darren Roberts

Another rough idea problem!

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Hi Guys,

1992(K)  hard dash de-catted.

I've googled virtually all the rough running issues and come up a blank with this one, so any help appreciated.

A while back the valley gasket was replaced, and to be honest it's never run right since, due to a whole series of issues. 

So to cut to the chase, I've followed off LandyZone the process for resetting base idle, namely.

  1. Clamp the hose in the back of the plenum between inlet manifold and idle control valve.
  2. Unplug idel control valve.
  3. Warm engine up.
  4. Adjust base idle screw onto of the manifold to get 500 rpm +/- 20 rpm.
  5. plugin idle control valve.
  6. Unclamp the hose on back of the plenum.

I've tried this twice and I can't get it to ticker at 500rpm consistently. The ECU Mate show RPM fluctuating all over the place, so when I get to the end of the process, its. no better than before. Could there be something else causing the rpm to fluctuate (sometimes by 100 odd rpm or more) when the idle control valve is isolated. So I'm figuring if its won't idle smoothly with the idle control valve isolated, it's got no chance when it's no isolated.....

So far it's had

  1. New rotor arm
  2. New coil
  3. New dizzy amp
  4. New plugs
  5. New HT leads
  6. Replacement ECU.

1 lamba is showing 128%, the other lean.Its running green fuel map.

All ideas appreciated.

cheers

Darren

 

 

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So, I assume it's a V8, guessing hotwire...?

Any chance your lambda sensor/s are knackered / oiled up?

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Given you had issues after valley gallery, I'd hazard a guess that there is a substantial vacuum leak somewhere, oscillating idle is classic symptoms.

Maybe the Valley gasket, plenum joints, hoses etc.

 

 

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Thanks guys. 

New valley gasket, new host between air valve and inlet manifold. So I will check the rest of the hoses and maybe re-torque the manifold..

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Given you said it has not run right since the Valley gasket was replaced..... I'd be going round the inlet tract with brake clean while running trying to find the leak, the idle will raise when you squirt flammable stuff at any leak.

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Ok checked for leaks with brake cleaner, couldn't find any at all.

Changed the ECU for another, reset the base idle a couple of days ago and ran rough when warm. Pull it out tonight and it ticked over really steadily. Turn it off to move the cars' nd it struggled to start without foot on the gas pedal. Anyway got it running, took for a test drive, ran until it was fully warm.

Here's the ECUMate output

https://www.icloud.com/photos/#0YwqOOC8svktNJm3MpC2i3jCg

Does this give any more clues?

cheers

 

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On 10/17/2018 at 7:07 PM, Darren Roberts said:

"...... it's never run right since, due to a whole series of issues. "

if this is still an issue, my thoughts: that maybe the problem lies somewhere in that whole series of issues. Time to retrace your steps,  perhaps state here what w as done - that may clarify things in your own mind as well. Also were all the ignition bits quality items - sometimes can be problematic if not. Standard ignition amps are never brilliant imo, aftermarket ones provide more of a punch. Could also be interesting If you can get a vacuum guage on to the inlet manifold - fluctuations will point to induction leaks rather than ignition. Let us know what happens

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Thanks Joe.

Originally it was leaking from the rear of the block, so a mate changed the valley gasket for me.

The breather t piece between the charcoal canister and the plenum was damaged, so replaced. Somewhere along the way the temp sensor  plug and injector no1 got transposed, and eventually managed to sort that out. Then I invested in the ECU mate, and it showed errors on temp sensor and throttle pot - a broken earth was the root cause there, so sorted. The ECU mate also reported that it was running white program, the cats have been removed , so I did the resistor change. It no longer "sticks" as my wife kindly put it - as it was no longer running in limp home mode.

 

But it still would have a very rough idea, so the rotor arm, leads, coil and dizzy amp where all changed (I usually go for Bearmach) and the dizzy put back as per factory because somewhere along the lines it had been moved 180 degrees out. Then the hose between the air control valve and the plenum was changed, and the air control valve itself.

Its a lot better than it was but still "hunts" when warm. I'll try the vacuum gauge idea - thanks....

 

 

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If the idle was also off before the valley gasket change (leaks from the rear of the gasket?) then the gasket change didnt solve the idle problem. 

Looking at the video clip the throttle display value looks low, (0.19v) so you might want to check the throttle pot setup. Ecumate manual says:

"The throttle pot voltage should be in the range 0.3 to 0.5V whes:n the throttle is closed. This corresponds to a percentage value of about 3 to 5%. On full throttle the voltage will be around 4.5 to 5 volts. The ECU can cope with slight variances in the voltage but it is important for correct operation that the throttle pot is adjusted so that it meets the minimum values". (Btw the ecumate looks like a powerful tool to have - never seen one in action before)

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Hi Joe,

Yes got rained off so maybe another go tomorrow with the suggestion re throttle pot. I didn't think there was any adjustment on these, I have another so I might swap it out and see if that gives different values. 

Today I out a vacuum gauge on the hose that normally fields the sphere which is the reserve vacuum for the cruise control (mine is disabled). On the vacuum gauge the readings constantly fluctuate. I think this is part of the problem to set base idle and 500rpm +/- 20 rpms is impossible as it's fluctuating by a couple of hundred rpm either way.

I also pulled the top off the plenum today - no gasket? So I used some instant gasket to see if that made any difference but didn't appear to. Previously spraying brake cleaner everywhere didn't seem to affect the revs, but with it "hunting"it was hard to tell for sure.

Yes the ECU mate sin't made anymore, cost my £80 second hand, and certify not parting with it any time soon!

cheers D

 

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Swapped the throttle pot today. At idle it's giving 0.14 volts so very similar to the other one that was fitted. Check the ECU Mate output and it looks like the voltage is increasing and decreasing uniformly with the throttle going down and back up, maxing out at 4.5 volts at full throttle.

It goes to idle mode ok when not pressing the down on the throttle.

Also just reading back on the thread, the valley gasket was changed due to a coolant leak, not air leak. It wasn't until I git the ECU mate that I realised that the TPS and Coolant Sensor weren't working properly due to the breakage on the common earth, and that it was still running a "with cats" fuel map, ah=n therefore running in limp home mode. The next step was changing the components out as mentioned above and ensuring that the dizzy was in the right way around...

I'll have a another read of the documentation, the key thing I need to stop the tick-over from fluctuating when setting the base idle. .......

 

Edited by Darren Roberts

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Would the tick over be erratic if the timing was out? I did time it up but wondering if the dizzy has moved?

Edited by Darren Roberts

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Yes, it's quite possible the timing being wrong could be making it hunt. The timing marks can often be incorrect on the pulley wheels too, so it's not beyond the realms of possibility it's way out despite looking correct. Take plug no 1 out and use a long screwdriver or similar to check where tdc is in relation to the mark. 

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Today I reset the throttle pot as suggested by Joe1. I now have .32 volts and 6% on the ECU mate readout. Checked the timing at 6 degrees and took it for a run. It ran fine when cold, cam back after about 3-4 miles. Water temperature was 76 degrees, feel 30 degrees. When I pulled onto the drive it started to ticker roughly again.

I tried setting base idle but the revs were jumping all over again.

I swapped the MAF over, and gave it a couple of degrees more timing(now 8 degrees) but to no avail.

I'm pretty confident that there is no air leak around the plenum chamber.

So to recap it's had:-

  • New rotor arm
  • New coil
  • New ignition amp
  • New air hoses at the rear and front of the plenum.
  • New temperature sensor.
  • New leads
  • New plugs last year (done about £1k miles if that).
  • Replacement throttle pot (second hand but tested and gives the expected output on the ECUMate when the throttle is pressed and released.

No faults showing on the ECU Mate tool.

Swapping ECUs makes no difference.

Swapping MAF's makes no difference.

Runs lovely when cold, and hunts when warm. I'm sure the base idle will be a doodle to set once I can get it to ticker smoothly when warm.

What else could cause it t hunt when warm?

My next port of call was going to be new fuel filter and new fuel temperate sender.

 

 

Edited by Darren Roberts

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Did you check that the timing marks are actually in the correct place, though? 

From here:

http://www.v8engines.com/electrics-1.htm

You cannot trust the indicated timing marks on your engine's bottom pulley. We have found them to be up to 20 degrees out in the worst circumstances.
To check this, it is required to remove No 1 spark plug and rotate the engine (using some form of probe down the cylinder), to ascertain if No 1 piston and the indicated TDC timing marks do actually align asindicated TDC on your pulley.
Especially if your engine is other than the std. production one in the std. production vehicle it was originally fitted to.
If your indicated TDC pulley (reference) mark is wrong, then all you do and all we advise, will never stand a chance of achieving what's expected. This also applies to the information given above, so ignore this section at your peril.

 

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What about the idle stepper, those were known to get sticky? I wouldn't splash for a new one but borrowing a known-good one might be a goer?

 

 

Mind you, at this point I'd just Megasquirt it and have done but you know me... :ph34r:

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Hi Guys,

Yes sorry forgot to mention, new stepper motor.

On the timing side I checked tic was at point number 1 when I put the dizzy back in properly after it was put in 180 degrees out after the valley change, but I will go back and check that today as I didn't realise the timing marks could be so badly out.....

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Ok timing checked, "appears" to be ok. Really hard trying to check that even with aid of 14 year daughter, seems like the crank will move a fair distance whilst the piston is at top dead centre?

Not clear whether the timing should be checked with the vacuum advance connected or not. Tried 6 degrees, 8 degrees, 10 degrees and 12 degrees. No noticeable difference. 

Torqued the plenum down way tighter than it should be, just in case there are leaks.

**** out of ideas now and really contemplating getting rid of it, as it seems more hassle than it's worth.........any other ideas I should try before I either send it somewhere to be fixed or auction it on the bay of sins......

Edited by Darren Roberts

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Got the pipe in rear of plenum to the fuel pressure regulator?

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I know you've done lots of it already but it's worth downloading the troubleshooting guide PDF from the technical archive and going through it step-by-step, not skipping ANY parts even if you "know" it's OK, times like this it's easy to go blind to stuff your brain is sure is "OK".

I haven't re-read the thread but are your lambdas still massively out of whack?

Also, I'd question aftermarket ignition components, it's partly superstition but RV8's really do benefit from genuine ignition bits and can be really sensitive to lower quality bits (as even the good stuff is marginal). I've had one refuse to fire AT ALL which was fixed by a set of NGK plugs.

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If it is running fine when cold I would consider a temperature sensor issue. I know you say you have changed it, Have you changed the right one? Have you tested it? Does your ecu mate show the engine temperature?

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Hi Guys,

Thanks for the words of support. 

I will read the troubleshooting guide tonight. Can't do anything now until the new fuel filter turns up later in the week.

Temperature sensor (water is new), swapped old one bad, no different. ECU mate shows water and fuel temp. Can get the water up to 86 degrees, fuel to 30 degrees. Running green program so lambdas not used? If you go up about 5/6 posts there is a video of the ECU mate readout. Pretty sure the lambdas output hasn't changed since then.

I will read the troubleshooting guide tonight - I've been relying on the ECU mate manual, and British Atlantic and some bits of RPI pages to date.

All components are at leats Bearmarch of genuine LRO, the coil is Lucas.

Hose from plenum to fuel rail? Not sure which one this is so I will check.....

 

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