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Hesitation off idle, poor idle


Rgardner01

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Ok been chasing this problem for a year now and I am just fed up....

Car starts up cold fine, idles strong and has sharp throttle response. After a few seconds when the ECU goes into closed loop mode the car idles a little rougher and has a large hesitation when gas is applied. If I stab the gas the engine will just go quiet drop to 500 rpm and hang their then after what seems like a second it clears up and catches up. Its almost like the gas and ignition shut off.

The car drives fine down the road but starting from a stop and applying throttle too quickly below 2000rpm will result in the car hesitating, almost dying and then catching back up.

The issue does seem to get better once the car reaches 80C but not fully….but this takes awhile with a large radiator.

No check engine lights ..constant code P0462. Cant get it to go away.

The Car has done to it

RC injectors

EU Sport 350 ECU

No Cats

2 new Oxygen sensors

New MAP sensor

New plugs

New fuel tank pressure sensor

New wires

New Coolant sensor

New fuel pressure regulator – Aeromotive adjustable

EGR blocked at the left exhaust manifold and at the split section of the EGR pipes

Air injection disconnected.

Analysis

Issue seems to start when the car goes into closed loop mode

Fuel pressure running is 62~63 psi

Fuel pressure after stopping is 55 psi

Fuel pressure remains at 55psi for well over 12 mins….i quit watching it…its not leaking

Vacuum at idle is 18 in/m

Below are snap shots of the car running with OBDII Scanner….any input is appreciated. The part that jumps out at me is the knock sensor 32 degrees retarded?? Not sure if that is even possible.

Any suggestions????

Thanks

Ray

<a href="http://s927.photobucket.com/albums/ad118/rgar973538/?action=view&amp;current=Untitled-2copy.jpg" target="_blank"><img src="http://i927.photobucket.com/albums/ad118/rgar973538/Untitled-2copy.jpg" border="0" alt="Photobucket"></a>

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Edited by Rgardner01
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Hi Ray,

Doesn´t sound like you are having any fun.

Have you considered putting back the stock fuel pressure regulator? Your fuel pressure seems a little on the high side and might be consistent with some of your other data (trims etc).

The knock retard doesn´t seem right and I couldn´t even find PO462 in my Lotus lising. Seems to be fuel related in other listings.

Cheers,

Mike S

Edited by mike_sekinger

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Well I have been trying different fuel pressure settings from 50~70 psi. The car seems to run a little better at 60+. I read in the manual fuel pressure running is supposed to be 61psi while the engine is running, 55 when it is not...I know many people have mentioned 55 as the stock value...so kind of cinfused on that one.

I guess I'll purge the engine of all EGR nonsense and air injetion bits to eliminate any air leaks from those.

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Hi Ray,

The fuel pressure is specified in terms of ranges.

- standard value should be 55-61psi while running - clearly higher under boost

- fuel pressure in the rails can drop to 12psi when the fuel pump is not running - e.g when switched off

It sounds like you may be over-fuelling. What do your plugs look like? Are they looking rich and very sooty?

Cheers,

Mike S

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Hi Ray,

Like Mike, I checked my service manual and can't find a reference to P0462. So I searched on-line and according to most google hits P0462 is 'FUEL LEVEL SENSOR LOW VOLTAGE'. So what is you fuel gauge reading?

It does look like you are over fuelling on bank 1. Could it be a leaky injector on bank 1 or an O2 sensor problem on bank 1.

I assume that you have done a reset on your ECU. How quickly after a reset do you get a long term trim of -11?

I have looked at some old logs I took for my car and worst case is a long term trim of -4. However, I have standard injectors so you should expect mine to be lower.

Regards,

Peter.

Hi Mike,

What knock retard are you getting on your V8s? I'll try to remember to check on mine at the weekend.

Regards,

Peter.

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I checked my OBDII logs all the way back to 2007 the PID KRAITD "Knock Retard Applied to Ignition Timing Degrees" has always been reported as 32. It never moves. I think its a canned or frozen value.

The -11 trim value is large and very suspect!

Wayne

Edited by WEllison
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The Older I get the Faster I was

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Thanks guys. I'll try blocking off the secondaries and reseting the ECU. I have placed two new 02 sensors in the car but I will inspect the connections and wiring. Good to know the 32 degrees is a canned value. I'll also pull the plugs and see the condition to see if I one cylinder shows up worse then another .

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Hello Ray. Sorry to see you are having a problem like this. I know how frustrating it can be. Have you solved this yet? If not I have a suggestion.

I had a similar problem of hesitation (on a Mazda Miata) and it turned out to be the TPS (throttle position sensor). The TPS is basically just a potentiometer and the wiper/windings got gummed up giving erratic output across it's range. I was able to take the TPS apart (carefully) and spray it thoroughly with electrical contact cleaner. This was done about 2 years ago and so far the problem hasn't returned.

Hope this helps.

Cheers.

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Had another thought.

Could it be that the charcoal canister is not purging correctly? Either keeping too much pressure in the tanks, or purging all at once and causing the car to choke off idle?

Or the hose between charcoal canister and intake manifold is leaking, or the one way valve has failed?

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Travis

Vulcan Grey 89SE

 

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  • 2 weeks later...

Well had some time to fool with it. Knocked the fuel pressure down to 55 psi and replaced the EVAP breather and also played around with the TPS sensor. I drilled out the TPS bolt holes so I had some rotational adjustment to it. Bolted it on making sure it had some pre adjustment to the throttle shaft. Runs better but still feel there may be something very slight. Will drive it a little bit and replace the TPS with a new one. I am still planning on removing all of the EGR and Air Injection to insure there is no air leaks there.

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  • 3 weeks later...

Well the TPS sensor did not work. Replaced my new fuel pressure regulator again with a corvette one. That ended up showing only 39PSI so I replaced the fuel pumps . Still runs like garbage. I put my adjustible fuel pressure regulator back on since I believe the corvette one is not correct and adjusted it back up to 55 psi at idle. I can see the fuel pressure hold steady, spike upwards to 60+ when hitting the gas, and holds 45 psi after shut down and was still on 40 psi after I mowed the lawn. I dont think this issue is fuel system related...or alteast leakage

Its very odd because the car will start cold and run ok for a second then it goes to hell once the ECM takes over. Runs extreemly rich , rough idle on RH side and still has the hesistation. I am running out of things to replace.

I have the EGR blocked at the left exhaust manifold and at the split section of the EGR pipes & air injection disconnected and no cats

So now this damn car has on it

New MAP sensor

New fuel tank pressure sensor

New plug wires

New Coolant sensor

New fuel pressure regulator – Aeromotive adjustable

New Fuel pump

New waste gate solnoid

New TPS sensor

I have tried running this car with all external vacuum lines disconected to eliminate EVAP or air leaks but I see no difference.

I guess I might as well tear the intake off and replace the coils, and new plugs again. I will try to replace the canister also , although I have tried it blocked off with no change.

Does any one have a V8 who would try out my ECM and see if the issue follows the ECM?

Analysis

Issue seems to start when the car goes into closed loop mode

Fuel pressure running is 55psi psi

Car clearly is running rich.

Car starts very hard when warm....struggles to catch and then has to clear its self up before it sets into a idle.

Really really close to calling it quits and parting this car out since its no good to me like this and its been a year+ now chasing this issue.

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Hi Ray,

Could it be a problem with your ECU? Can you try a different ECU?

One issue someone else had on the forum was that the O2 sensors were swapped round so the sensor from bank 1 was connected to the bank 2 connector and the bank 2 sensor was connected to the bank 1 connector. This lead to the obvious situation where the ECU couldn't control the fuel air mixture correctly.

I hope you manage to resolve the issue(s).

Regards,

Peter.

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After lots of trials on sensors and the EVAP system I saw what appears to part of the issue, the car is running in open loop for an extended period of time. The car is undriveable at this time. I am still getting a P0462 for the fuel level. I disconected the entire sensor and resarted the car...the car went into closed loop and set a MIL lamp...normally it does not set a MIL lamp for this. Drove it for an hour and it drove like I remember from when it was new.

I am not sure if this sensor causes some of this condition or not but I will check the car agian in the morning and see how it reacts from a true cold start. Does any one know if the P0462 code triggers the ECM to enrich the mixture or anything?

Still not sure why it takes minutes for this car to go into closed loop. I am guessing maybe ECM programming?

I verified coolant temps from cold to warm up and they appear correct , IAT temps check out , MAP and BAR check out.

When I run the diagnostics the 02 sensors appear to check out ok for heat up tests...is there any other way to verify the heater circuits and reaction time from cold to hot?

So I guess if the Coolant and 02 sensors check out it must be the ECMs canned program? - Keep in mind I have never had this ECM run 100% correct and it was off of a UK Sport 350.

How long should the car run in open loop before going into closed loop? I am guessing seconds right?

Has there been any updates to the ECMs idle warm up circuit since 98 / 99 S350 ??

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I will have to try this. Looking at some of my old computer screen shots I can see some values below 0.05V....I saw a 0.005V on one of my screen shots in closed Loop. I will check the wire harness tonight and clean all connections agan. I have thrown multiple oxygen sensors at the car so I dont believe the fault lies within the sensor itself if this is the root cause of my issue.

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  • 10 months later...

Well after chasing this issue for some time I have traced the it to my upgraded injectors. It appears that although some may run RC injectors with out fault they where causing my issues. Not saying that RC injectors are bad but they just where not working in my car. Through my investigation it looks like the RC injectors ohm out at 16.2 ohms, the stock injectors are 12.2 ohms.

My theory here from what I have read about solenoids and injectors is , although both are" high independence injectors" it appears the added resistance of the RC injectors creates a very quick open close time, although this sounds good it cuts the spray duration time down, in turn my car was running lean over, trying to compensate which just kept it in a death loop of too lean too rich....right or wrong something was up with the upgraded injectors.

The car now idles nicer, no hesitation when cold , no more hard starts.

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  • 4 months later...

Congrats on finding the solution, and a big thank you for taking the time to post the final solution to your problems. This thread is a very valuable archive.

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  • 10 months later...

I just wanted to update you on this issue as I am sure many people suffer from time to time rough idle, extreme popping out of the right side exhaust, rough idle after warm up vs cold and even hard starting.  

 

Although I thought I had this fixed a year ago, shortly after I posted I realized my efforts where not correct...basically I was dumping enough fuel to hide the underlying issue.  

 

Anyway several months ago I was told to check the cam positions.  Now I do my own cam set up and belt changes and even from time to time have had them done.  I have checked my work against actual shops and everything they did always checked out the same as what I was doing  ( Belt tension and tolerance pin alignment ) 

 

It wasnt until had the engine out and at the same time was told by another Lotus owner to check the cam timing, especially the intake on Bank 1.  I checked it...."tolerance pins" went in, showed holed lined up, and tension was right.  After starring at it I noticed the pins although correct where not true vertical. Looking and looking at it I began to be more critical of it and decided to take the cams out and reset everything to "0" tolerance.  After loosing the cam pulleys, adjusting and tension belt so the cams where set to the "SETTING PINS", I checked again with the tolerance pins.  Not only where they straight now, they actually went in much deeper then before.    

 

Although what Lotus is doing with the cam alignment is rather simple , the checking method can cause error...especially if your doing it in car.  If you have the parts out of car you can see how the set pins can wobble in the cam journal towers, or even become skewed as you screw then into the cam, and they touch the sides of the cam alignment holes. If the cam towers had more thread length this probably would not happen. 

 

What was going on with my car was the Right side Bank 1 Intake cam was out of tolerance...think advanced.  Bank 1 intake cam is the reference cam so if its out compared the the others ....weird things happen.   So the car would start up and run ok, then once the computer took over into closed loop it would go to hell because of the two sides have different cam durations.  The car would pop out the right side, idle poorly and seemed like it less grunt down low.  

 

Since re-setting my Cams to "0" with the set pins while doing my belt tension and changes,  the exhaust popping is almost gone...in fact it only shows when the car is running warm.  Car runs better, idles smooth and has its grunt back.  If you have these issues, aside from checking the other items we all see go wrong...check cam timing...be very critical of its position..especially Bank 1 intake.   Chances are its part of the issue. 

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