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High Revs / Vacuum


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The IAC was replaced a couple of months ago when I got the car. It had this same problem (high revs when stopping). Once replaced it was sorted.

 

Right now, everything is connected as it was (ie vacuum pipes) but as I posted earlier, the EBPV valve is stuck "open" and I cant say if that's 100% or a bit less but it's been like that since I got the car 3 months ago and has done 1500+ miles since.

 

I wouldnt say the the engine runs "rough" nor would I describe it as "100% perfectly smooth" at tickover. Having said that, the RPM needle doesnt jump around or anything and I wouldnt say it's misfiring either at idle or on the run.

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I wouldnt say the the engine runs "rough" nor would I describe it as "100% perfectly smooth" at tickover.

 

 

Sounds like my car. I often wonder if that's normal or not.

 

It really won't hurt if you disable that Throttle Jack. If you have a ball bearing or even a rubber cap to put on the outlet of the throttle jack solenoid and a few zip ties to secure the quadrant to the trunking above it, it should only take 10 minutes to carry out the mod (assuming your solenoid is in the same place as mine). It will certainly help with the faultfinding and it is completely reversible.

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  • Gold FFM

I wouldnt say the the engine runs "rough" nor would I describe it as "100% perfectly smooth" at tickover. Having said that, the RPM needle doesnt jump around or anything and I wouldnt say it's misfiring either at idle or on the run.

The idle is known to be not very smooth on these lumps. I worried about mine, but it's absolutely fine. Crank it up to 1200 and it's much much better sounding. Just under 1000 is where the hesitation pops up. It is a performance engine from the 90s and was pretty much the norm for that sort of thing back then.

You need to loose the throttle jack completely to rule out any strange stuff.

Check the Tps. - set it up to about 0.53 v and make sure it goes fully to 100%

The idle rpm you can change in freescan. Maybe this has been inadvertently adjusted in the software.

I can't see the data on an iPad..... Does the O2 sensor swing in voltage ??

If you have a read of the freescan manual it helps you to compare back to the data.

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I'm going to block off both off this vacuum tubes this weekend. I check the desired idle setting.

The O2 sensor does change BUT looking at the Freescan it spent 90% off the time below 0.3 or over 0.5.

I need to work out whether it's working properly or not and if not theme relate it when I get the new exhaust on.

Having said all that I gave the car a hard run last night with plenty of high revs and it appeared to idle better and didn't CEL on stop. I wonder if resetting the BLM and driving around local roads just hasn't given it enough data to set itself up again? I know the manuals say drive at over 20MPH but maybe it needs a good and varied run to learn?

Anyhow I'm off to find some ball bearings and get that done. Will report back.

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  • Gold FFM

Good man.

You need a relearn that's fully done. Have no idea what the factory protocol is but.

Reset everything

Start up from COLD

Idle until fans kick in.

Take for a drive - a nice mix of spirit and sensible

Got for 10 miles........at least.

A quick spin round the block when starting with a hot car did NOT do it for mine. Follow the above and that's the best you can do

The O2 should sway nicely and look pretty random like - that shows it's working apparently. Is what mine does. But at startup it doenst change much as it's not in closed loop and I believe it doesn't have the ability to change fueling if I'm correct...

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OK. Reset everything. Blocked off both vacuum pipes - couldn't find any ball bearings so went with looped-back t-pieces.

Fired it up and waited for AGES until the fans kicked in. Used Espritmon to monitor everything and all good. Engine idled quite smoothly - i'm sure better than before.

Once it was warm, it needed fuel, so I headed off for the petrol station. Straight away I could tell that slow speed running was massively improved. Previously it was a bit lumpy until you got your foot down.

 

So absolutely no issues at all, runs like a dream, so much more responsive on the throttle and much, much better to drive.

 

This mod should have been done day 1.

 

Is the IAC quadrangle tie-up OK?

 

Thanks for your help guys

 

 

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  • Gold FFM

Sounding like a proper result.....

I just knew when I'd finally fixed mine after lots of trying......and the wait for them fans seems at least 10x longer than it should be

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Interestingly the A:F ratio stays at 14.6 pretty much the whole time. I suspect that the old setup was continuously adjusting the fuel mix, throttle, etc. and now it just works!

Tomorrow morning (before the rain comes) I'll take her out for a good run and confirm it's the same!

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  • Gold FFM

A/f should be at 14.7 by the book. I reckon 14.6 is close enough to count as spot on. It's the rich side of perfect rather than lean ( which is bad )

Get her out and drive it's the only way to know for sure - but I reckon you've got a warm happy feeling about it!!!!

I wouldn't try and unpick the fault - I buggered about with mine for a fair few hours before I got it right......imagine if you were paying a garage for that!

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So absolutely no issues at all, runs like a dream, so much more responsive on the throttle and much, much better to drive.

 

 

Great to hear. I'll keep my fingers crossed that it continues that way. Of course, with the car fully warmed up, it probably does feel better to drive than one which is completely cold.

 

Keep an eye on the loopbacks, especially on the throttle jacking capsule. That red/black(?) vacuum hose is subject to a lot of heat, so may perish in time (causing vacuum leaks). A loop at the other end may have been better and perhaps less conspicuous at MOT time :P

 

I didn't realise you had a BOV (or forgot). Is it active? If not set and maintained properly, this can cause problems, too.

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OK, thanks for that. On my outing yesterday I did a good run up the motorway for 40 miles and it ran great.

On the way back it started to rain and I thought it would like the denser air but it didnt seem quite as happy. That may just be me going a lot slower anyway. Right now I cant run any monitoring inside the car because the under-dash ALDL doesnt work as well as the rear one.

I also prefer the output from Espritmon.

 

I'm going to get the cable extended from the back when I pull out the 6-CD changer cable that's not in use any more and feed through the same hole/route.

 

Then I'll give it another run, possible in this lovely damp weather we have this week!

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