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Discussion Starter #1
Ive just replaced Rh head gasket on my 99 4.0 L it was blown on #3 to the outside of the block . no damage to head or block& was otherwise running OK . But started it up nowp& wont go over 1600RPM just sp[its & backfires . Ive checked the ign leads order 3 times & definatly correct order all firing . No engine check light on so now what do i check thanks
 

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GEMS or Thor? NAS with SAI or elsewhere without? I've just done a GEMS with the exact same problem, gasket blown out the side on one cylinder and the head needed 6 thou skimming off it. I also only did the one, the other isn't broke so why fix it?
 

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1995-2002 Range Rover Classic
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if it is a bosh management engine, check the coil connector on the left side coil versus the idle control valve, often they are cross connected.
 

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JACK'S GRANDAD
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I also only did the one, the other isn't broke so why fix it?
Because you've already done 80% of the work maybe?
Not the smartest move in my opinion and experience.
Doing the same thing now with wheel bearings and seals. Got both hubs off to replace the discs, may as well replace the bearings and seals while it's apart. Plain common sense comes to mind.....

At least now everyone should understand why I'm a prick about folks putting at least their country, when posting.
 

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Discussion Starter #6
engine says 42D 4.0 air flow meter says Sagem made for japmarket but imported to NZ 02 . Coil packs behind engine & drew pics of all connex . tripple checked Rh head all 140psi ish cold throttle closed so didnt touch it Engine.runs smooth until 1600RPM other 1 checked for hardness & straigtness ok tearing my hair out now . cheers
 

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That's a GEMS motor. The only thing that comes to mind is the airflow meter. If it is disconnected that can cause the symptoms you have but it will also make starting difficult, usually it'l start but won't idle unless you feather the throttle.
 

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JACK'S GRANDAD
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So you're in New Zealand?
Does it have cats?
Or just post up everything at once.....
 

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Discussion Starter #9
Yep down under . Cats been cut out & headers fitted the 02sensors still in though .. Is there any test I can do on the air flow meter ,that was my first suspicion . I didnt touch it or clean it just put it aside .. Trying to get a garage to look at it or do diagnostic check at this time of the year is near impossible . Its like it had a rev limiter cutting the ignition at certain rpm .cheers
 

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JACK'S GRANDAD
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Add your location and year etc to your signature
Did you search for your symptoms? IIRC its a crank sensor issue at times.
Last one I had in here that did that, was the exhaust that was stuffed full of something and was retricing output flow. Disconnected it at the Y pipe and checked, revved freely

Martin
 

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If the TPS fails on a GEMS, it will not rev over 1700rpm. Check if it's connected properly after the rebuild.

Filip
 

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Discussion Starter #12
Well some good news found a garage that will have look at it , most wont touch RRs bad rep & no dealer network inNz . But i cant see any dianostic plug , looked by the ECU under the seat but nothing there .
 

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In the passenger footwell, up underneath the dash next to the centre console.
 

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1995-2002 Range Rover P38A
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Pull the codes and fuel trims (long term and short term) using a scan tool and post them. They may clue you in as to why the misfire is occurring.

Often times, running problems after doing engine work can be traced to air leaks via accidentally disconnected or incorrectly connected vacuum hoses or wires. This is just a guess, so take it with a grain of salt.
 

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Discussion Starter #15
Yep that was my first thought as happened on my old 98 the inlet manifold gasket was leaking . So ive poured petrol beside the injector s to see if it revs up but no such luck . Well see on tueday
 

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Discussion Starter #16
No scan plug looked under glove box even dropped it down , an ECU but no socket for scan plug everything is connected to something also took panel under steering l off not there either nor under seats nor in engine bay . now what this thing is driving me crazy .
 

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It's there, right underneath, up close towards the front of the car. Get your head in the footwell and look up. I maintain a LHD car as well as my own RHD cars and it is on the passenger side on both.

OBD.JPG
 

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I would expect 175 p.s.i....try another pressure gauge...but 140 not low enough to cause a misfire, unless engine management is misinterpreting it. Poor connection Under a coil pack has been suggested elsewhere for misfire. The GEMS has an earth hidden under the hooter mounting bracket, between the battery and the fuse box that might need cleaning up.
 

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Discussion Starter #19
Ok guys looks like its crank cam / angle sensor so where is this on the engimnne cant see anything on the front of the cam cover . . & if I get them out is there any way to confrirm they are faulty . cheers .
 

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JACK'S GRANDAD
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Front cover, but its hidden. You can see the wires and make sure they are connected good and tight. Whenever that plug is undone, it's pretty much a given that it will break. Insulated spade terminals work fine if it does break.
 
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