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Developed a flat spot when accelerating after having a service.


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#1 NQRSoobee

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Posted 26 May 2017 - 09:06 PM

Hi All,

 

  Had my 2nd Gen RX serviced on Wednesday and it's now developed a flat spot when accelerating between 1800 and 2500 rpm.  When I give it a real boot the EJ25D gets up and boogies no matter what revs it's doing but when using partial throttle it "lags" terribly.  Best way to describe it is like driving an older carby car with a kettering ignition system and the vacuum advance is disconnected.

 

  I chatted to the mechanic who serviced it and he said it sounds like the MAF is having issues.  I've already checked for cracks in the connecting tube from the MAF to the plenum, there are none, all the clamps are tight and the wiring clips on neatly to the MAF so I'm running out of ideas on that front.  I intend to pull the MAF over the weekend and spray clean it.

 

  I also put injector cleaner in the fuel just in case it's an injector/fuel issue.  Unfortunately I also did refuel it the same night it was serviced so I do wonder if I got an off batch of juice but I reckon that would cause problems no matter what the revs or throttle position.

 

  Don't really know what's causing the issue with my Soobee but some useful hints and tips would be appreciated.

  Ta muchly.



#2 NQRSoobee

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Posted 27 May 2017 - 01:42 PM

Well I've cleaned the MAF and almost no change.  When accelerating in any gear from 1400 to 2000 or so RPM it's like someone has halved the throttle setting.  I can't hear a vacuum leak, it idles smoothly, and I forgot to check the CEL codes.  Doh!  Anyway connected the two black wires and I now have a code 12.  Checked a few forums and most advise 12 is Starter switch or circuit.  Er... dunno what that has to do with it as it starts fine but doesn't run nice.  So I'm more perplexed than ever on this issue.

 

Constructive thoughts appreciated.



#3 NQRSoobee

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Posted 27 May 2017 - 03:03 PM

Did some more web surfing and found another forum that claims to have solved a flat spot issue with 2.0R engines.

 

http://forum.liberty...=351672#p347362

 

Cross posted in case others find the discussion useful.



#4 Robert

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Posted 28 May 2017 - 04:54 PM

My car use to have the code 12 stored in the ecu all the time
Wouldn't stress about that too much.

What did the mechanic change?
If it was perfectly fine before that I'd be looking around the areas that were worked on
A wire might have been bumped/disconnected or something out of place.

#5 2.0R

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Posted 28 May 2017 - 06:42 PM

My 2.0R does this after a several weeks of driving, disconnecting the battery for a second resets the computer and it really zooms till the hesitation slowly creeps back in.
Still pulling hair out as to why this happens.



#6 NQRSoobee

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Posted 28 May 2017 - 10:16 PM

Cheers Robert, was thinking the same so I had a good squiz around the engine bay on Saturday.  Nothing obvious that I could see or find, I unhooked and re-clipped a fair number of the electrical connections which had no effect.

 

So it's a... dunno... the service was only the usual oil & filter change with a general once over to check everything is tight, clipped in, no major leaks etc (usual peace of mind that I haven't spotted something).  Only major work were the bellows on the steering rack needed replacing as they started to develop some cracks.  Given it's winter, cold concrete, better things to spend my time on and a reasonable rate to change the bellows meant I let him do the job as he has all the equipment, tools, etc.  If you happen to know of some wiring around the steering rack that might affect engine performance then I'm all eyes.

 

2.0R you might want to have a look at the thread that I linked up.  A good few peeps found giving the EGR a good once over or even replacing it stops the hesitation problem.  Can't guarantee it's a cure all, no harm if you give the EGR some TLC.

 

fwiw I put a new battery in it about 2 or so months back.  I can only assume the 12 code cropped up because of cranking... well clicking on a flat battery.

 

Oh and so far since I've had the beast I've bought & fitted to it: new O2 sensor, knock sensor, cam and crank angle sensors, fuel filter, and battery.  Was running quite well until the flat spot showed up.  Was going so well that about 2 weeks ago a Toy86 at a roundabout tried to hoof it away from me so I hoofed it as well and started catching him quite nicely but let him go when I hit the speed limit.  Was quite happy with its performance until the flat spot happened.

 

Completely forgot to unhook the battery today so I'll take a 10 mm spanner with me to work tomorrow and unhook it while I'm working.  Should be easily long enough while at work to reset the ECU.  :-)  The drive home will give me a good indication of what's what as well.



#7 2.0R

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Posted 29 May 2017 - 07:49 AM

Yeah thank you very much for the link, very informative reading, had me going for hours lol, had a good read of that, most interesting I found was the knock sensor learning over time to retard, one guy used freessm and a dedicated USB cable (not ELM) to take 3 degrees out of the timing seemed to fix it.
I'm shying away from dirty EGR and leaning towards this or finding a better grade premium fuel...



#8 duncanm

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Posted 29 May 2017 - 07:59 AM

It sounds suspiciously like the knock sensor retarding timing over time.

 

have you given it a good dose of UEC ?

 

As you say - worth trying premium fuel for a while to see if this fixes it (do the reset ECU trick again).



#9 2.0R

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Posted 29 May 2017 - 08:02 AM

Yes will be trying to find a better grade of premium (using united at present) and a reset till my cables arrive from the slow boat from china :-)
May also try UEC but this is a slow and steady flat spot that develops over time, I'm thinking if something was dirty it would come on much quicker and uglier...



#10 Barbbachello

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Posted 29 May 2017 - 10:45 AM

+1 try some premium to see if its knocking and pulling timing. Also try changing the plugs. Had the same issue with mine a few years back and fresh set of plugs fixed it


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#11 2.0R

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Posted 29 May 2017 - 02:14 PM

UEC blew a lot of shit out, whether it was just the foam burning or what I can't tell you,(a lot of blue smoke), changed the oil and stuck some treatment in the tank and after another reset it is really hammering.
Also filled up on Shell premium, see how it goes.
Throw some plugs at it soon.
Must be up for a service as the CEL is still on after disconnecting the battery, does anyone know if the CEL stays on if there is a service due?
(I do all my own work, waiting for USB cable to arrive to investigate).



#12 NQRSoobee

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Posted 29 May 2017 - 10:36 PM

As far as I know only Beemer's, Merc's, maybe Lexus's had a service advisory.

 

I understood that the CEL is only there as an idiot light to tell the Motoring Public (a.k.a. those who don't understand machines) that there's a problem that needs fixing.

 

For my problem the ECU reset helped a treat... so far okay but only the 20 minute drive home.  I find out tomorrow morning if it's truly fixed the issue.

 

Interestingly on the topic of RON, under the bonnet of my B2 it says 90 minimum for the EJ25D. So far it's being fed either 91 ULP or 95 E10 which ever is cheaper.



#13 NQRSoobee

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Posted 31 May 2017 - 06:54 PM

Well this gets better, my Soobee is slowly redeveloping the flat spot.  From the feel of it the ECU is relearning to put in the flat spot which means I'm giving it more boot to keep it going after it gets to 1.4k so when I hit 2.5k rpm it feels like it's massively cam-ing in and goes off like a shot.  Bit disconcerting behaviour in traffic.

 

Can't spot anything wrong with it other than maybe I'll have to pull a few air control components off and give them a good clean... now where'd I put my small ultrasonic bath.



#14 2.0R

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Posted 31 May 2017 - 07:35 PM

Mines creeping back also, its like a hesitation, or stumble when cruising and you floor it in the low rpm range.
Doesn't seem to effect if you driving spiritedly... yet.



#15 duncanm

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Posted 31 May 2017 - 09:18 PM

I had a flat spot in my old smoky EJ25 -- but it didn't progress slowly.  It turned out to be old HT leads which were broken down and sparking through the boots on the coilpack instead.

 

It was a very on/off behaviour.



#16 2.0R

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Posted 31 May 2017 - 10:31 PM

On an upside, the shell premium seems to be lasting a hell of a lot longer, pushing me to monitor L/100Km again.



#17 2.0R

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Posted 01 June 2017 - 08:10 PM

Sorry I can;t contribute to help and I will stop bombing someone else's thread, but it's back, stumbling between 2 to 3k
Shits me that much I cruise the speed limit in third.
Hope usb cables arrive soon.



#18 NQRSoobee

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Posted 01 June 2017 - 11:10 PM

Nah, don't worry about bombing the thread... main thing is to get discussion going.

 

Similar issue here; at present when low in the revs mine will chug a bit but not cough then as soon as I hit 2.5 k it smooths out instantly and goes like a scalded cat (heaps nice to be back in a manual too).  I'll let it keep going until it's "fully" misbehaving then have to do the old battery lead off reset ECU trick.  Sigh!  It's more fiddling setting up the radio that's the hassle rather than popping off a battery lead.

 

Might find my multi-meter and check the HV leads over the weekend.  The leads look reasonably recent so I don't think it's a dud lead but no harm in checking.  Beside that the old beast is running okay; very slightly weeps a bit of oil from a cam seal and same from both seals on the side of the gearbox.  Nice to have a car with cruise control again although the climate air controls are a little... basic.



#19 duncanm

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Posted 02 June 2017 - 08:44 AM

Nah, don't worry about bombing the thread... main thing is to get discussion going.

 

Similar issue here; at present when low in the revs mine will chug a bit but not cough then as soon as I hit 2.5 k it smooths out instantly and goes like a scalded cat (heaps nice to be back in a manual too).  I'll let it keep going until it's "fully" misbehaving then have to do the old battery lead off reset ECU trick.  Sigh!  It's more fiddling setting up the radio that's the hassle rather than popping off a battery lead.

 

Might find my multi-meter and check the HV leads over the weekend.  The leads look reasonably recent so I don't think it's a dud lead but no harm in checking.  Beside that the old beast is running okay; very slightly weeps a bit of oil from a cam seal and same from both seals on the side of the gearbox.  Nice to have a car with cruise control again although the climate air controls are a little... basic.

 

That does sound very similar to my old EJ25 behaviour.  Seemed to be a rev point at which it switched back on.  Would also go fine at low revs partial throttle, but give it a bootfull and it'd go slower.

 

I'd be making sure all your plugs and HT leads are good, and there's no evidence of arcing around the coilpack.

 

As above - make sure you give it a good UEC



#20 Barbbachello

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Posted 02 June 2017 - 09:14 AM

10000% check the ignition system. Start with spark plugs and work back towards the coil pack


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