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Idle problem too -- where to look?


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The engine is fresh,good compression, sparkplug new, wire (magnecor 8.5) new, injector newly cleaned and reflowed, new idle valve, no air leak (i think) turbo hoses (intake) are tight.

The engine dip to 400/500 rpm when I stop - sometimes it can recover and sometimes it dies.

There is a slight hesitation sometimes & stumble during acceleration.

I'm running out of option - do you think my FUEL PUMP not cooperating?

Also, the car has 48,000 miles, I believe I have not change the fuel filter since.

I will appreciate if someone has an idea where to look. Thank you.

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there is a post in the V8 section where you can find & build your own fuel pressure gauge, in case of...

interestingly you have really low idle, not the opposite as most with air-leaks. Anyway..

-as for inconsistent running condition under idle (you may know that in this idling-rpm our engines are nothing else than NA engines..), so use *brake cleaner spray* to test all joints and pipes on the plenum-chamber, spray it (as long as the engine is not fully hot ! -beware of glowing parts !!) under the plenum, undo and close the openings for brake assist, vacuum and Evaporative system. This way you seperate any possible external leak points. The brake-cleaner would pass any weak joint lines and get into the plenum chamber, followed by idling-rpm change

If your engines idles as it should under this arangement, you have to watch out for problems more external ..as so, maybe in those mentioned peripheric systems

Edited by Günter

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to name the things if I see them, that's what I call integrity..

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  • Thanks Gunter---I will try to buy a manometer/ pressure gauge and check the fuel pressure.
  • By the way, what is the fuel pressure @ idle & wot?
  • I will also get a can of brake cleaner and watch for air leak.

If I can't find the air leak, I will probably open up the top plenum again, maybe there is a wire

caught at the edge of the plenum gasket. It's really hard to work on that plenum.

If I will do it again, I plan to delete the EGR system (as per Mike's approach to EGR). Block it!!

I wonder if I can delete the SAI too?

Edited by Che
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  • 2 months later...

EGR has been a problem for me on an 02 that i've worked on.. it was cracked at the connection and would occasionally cause the engine to stall.

Modifying esprit's.. now that's fun..

PS... I AM NOT A CERTIFIED MECHANIC.. I Have chosen to help those in need, in the past and must not be construed as being a certified technician.

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  • 2 weeks later...
Guest modifiedv8engines

Mine had a hairline crack in the pipe that goes to the IAC valve. Installed new valve and still idle speed all over the place. Removed plenum again, found air leak, sorted that and car idles as it should.

Just remember that idle speed does not decay the instant the throttle is released but takes a second or two to stabilise

Paul

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Maybe this is way off, but I suppose you could always reset the idle through the ECU. Does the dip in idle coincide with the fans coming on for the AC?

If so, there is a Easter egg way to reset the idle with the throttle pedal, or you can use an OBDII scanner. if you need more info let me know.

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So...you recently had the engine out. I have done this also ...a few lessons and items I chased

1) Boost solinoid. Is it hooked up correctly? In theory you could have the vacuum / boost hooked to the wrong port. This will cause an issue..but you also will have odd boost feeling like feeling a loose clutch or wheel slip at high RPMs as only the wastegate springs will be holding boost so they open at 4~5000 RPM giving you the feeling of a loss of power

2) I had hesitation, hard starting - was aftermarket injectors - I assume yours are stock correct?

3) My hesitation just came back , but I have codes now - B7 fuse blowing on the EVAP. Have you checked your EVAP system. The solinoids are correctly installed and working? Wires correctly installed , wires not installed ? This could allow excess fuel fumes to be injected to engine ...and if its not at the right time / temp you will get all sorts of issues including hard starting

4) You could isolate the issue some by unplugging all vacuum hoses, plug them off a the plennum and throttle body. does the issue go away or get better? . Clear / yellow is EVAP, throttle body goes to boost solinoid. Small black goes to heater controls.

5) Does the car appear to be running rich? smell , excess exhaust poping?

6) Verify the vacuum hose to the pressure regulator is hooked up and tight...easily forgotten

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  • 3 months later...

Hate to be the new guy that goes around asking for the final result of a problem, but can you post what you found Che since it's been 7 months? I am sure it will be helpful for many owners for years to come. And I am sure the kind folks on here that offered you help would appreciate knowing what you did to resolve your problem in the end.

The engine is fresh,good compression, sparkplug new, wire (magnecor 8.5) new, injector newly cleaned and reflowed, new idle valve, no air leak (i think) turbo hoses (intake) are tight.

The engine dip to 400/500 rpm when I stop - sometimes it can recover and sometimes it dies.

There is a slight hesitation sometimes & stumble during acceleration.

I'm running out of option - do you think my FUEL PUMP not cooperating?

Also, the car has 48,000 miles, I believe I have not change the fuel filter since.

I will appreciate if someone has an idea where to look. Thank you.

Edited by lotusespritse
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This idle thing is a pain. Relearning does not do any good. Tried many many times and will not respond to learning process.

I replaced the idle valve (which another pain in the azz), occasionally it works but sometimes not. I replaced the

the fuel regulator....so far its working (knock on wood). I think its the combination of stuck idle valve and fuel regulator going downhill.

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Relearning does not do any good. Tried many many times and will not respond to learning process.

FYI, if you are trying to relearn the idle with the accelerator pedal and it is not working, chances are that your gas pedal is not getting 100% throttle. This is very common and there are a number of threads on it (a simple bend of the bracket will fix it temporarily).

Personally I would get an OBDII scanner which will allow you to check your throttle percentage, reset your idle by pressing a button, and maybe give some other clues about what the engine is doing.

Glad to hear you may have solved it though!

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Yes. The scanner I purchased came with its own software (which works too), but the Esprit specific one may be a bit more tailored to our cars.

Here is the one I bought and it works great ($29):

http://www.amazon.com/gp/product/B002PYBZJO/ref=wms_ohs_product

Just follow the directions to install it (a laptop works best obviously) and hook it up with the USB and vehicle connector. I use the one under the dash on the passenger side under the dash.

- Kent

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No problem, hope it helps!

btw - For the throttle position test you can simply press the throttle to the floor and see what the TPS box shows in the software. Mine was at 82%! A quick bend of the pedal bracket and you can go back to 100% at full throttle and get some more power.

The idle can be reset by a button in the software (reset all), but then you need to let the car idle through 3 fan cycles both with the AC off and the AC on. The idle will drop during the test when the fans and AC first come on, but then the computer learns what it needs to do to compensate. Then you are set.

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Yes I will do that...for the meantime, first, I need to fill R34 in my AC or idle is irrelevant.

One thing to another....I hope it's only filling up freon....you never know what is the next problem lotus will give you. :2guns:

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KENT - I just ordered one of the ElmScan 5 scanners for myself. Perhaps this is a dumb question, but while preforming the 'throttle position test'... Is the engine running?

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while preforming the 'throttle position test'... Is the engine running?

Good question actually... No. For the throttle position test you would want the "Key ON but Engine OFF" position of the ignition key. So with the engine off, turn the key forward until your gauges come on, fuel pumps hum, etc. but do not engage the starter motor or engine.

If the engine were running, the RPMS at full throttle would go very high very quickly!

For the idle reset and many other tests though the engine would indeed be running.

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Yes, it was the high rpms that concerned me. Thanks for clarifing this. I'm looking forward to 'exploring' with this new tool once it arrives. Sorry for hijacking the tread.

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My old integra type r and more recently my mothers runabout suffered similiar symptoms as this,turned out to be a faulty distributor (in mine) and a faulty coil pack in my mum's.perhaps the problem is in the ignition system?

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Timmy, Esprit (V8 ) tend to have a known specific problem if it comes on inconstant idling ..

and for your Lacetty , simply check the code discription for the airbag fault -and do what needs to be done ..instead of burning it down ;P

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to name the things if I see them, that's what I call integrity..

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Hey gunther, already know its error code 25,it's a design fault in the connectors they place under the seats for the seat curtain airbags that means the system "loses" the side airbags temporarily. Unfortunately even though there is probably nothing wrong with the airbags and it will still activate, because it's a safety device the warning light will still illuminate until reset. Chevrolet never admitted the fault. All it needs is disconnecting and reconnecting,the connections cleaned,and the code cleared, but unfortunately it costs time and money to have it sorted at a main dealer, and I don't have the time just now. Funny really, I wouldn't mind the problem on an Esprit! I'd probably sort it ASAP as well.....or just not get a v8 with airbags lol

But back to topic,didn't realise that was a known issue, I shall commit it to memory for when I'm looking for mine/finally get mine. Thanks!

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