Question about 1988 Jaguar XJ6

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My jag runs ok on idle and misfires under load

My jag runs on idle ok but misfires under load,ive changed the fuel filter and thats it,any ideas?????

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Do a compression test ?? about 180lbs anything less and it could need a valve regrind ,if compression seems ok then plugs and leads and use the bosch plugs with the 3 electrodes (for voltswagon) champion are **** and missfire.if still persists change dist cap and leads

Posted on Jan 17, 2009

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I have a 97 jep cherokee country 4.0 and can't find the fuel filter...my jeep acts like it's not getting.gas and wants to put? when im going 60 or so and i changed the fuel pump but its still doing it


if you follow the fuel rail gas line, it goes to the filter.
for sure.
4.0L 97 , we have the FSM to see all that , ive posted it 100s of times here. that link.
please explain the bog more clearly.
cold or hot engine or both.?
is it just tip-in throttle bogging , only then POWER catches, up?
while bogging can you go to WOT and see if it has full power now?
ever get a full 60k mile tune up with new spark parts. and filters.
is engine misfiring.
is engine idle too low rpm or too high with a hot engine?
is fuel old.
did car sit for long time ? unused?

"not getting gas" can be 2 things, bogging or misfiring
they are night and day different, one is like pulling a dead weight
the misfire is violent engine shaking,
see?
and 2 different diagnostic paths due to that ...

if wot is ok, then that implies fuel pressure is good. and filter.
see?

WOT = WIDE OPEN THROTTLE.
i drove a 99 XJ for 300k miles. and know it well..

free fsm
click fuel system here 96-2001 xj
http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service

see that page? page 14 in PDF
if you changed the pump, you had it in your hand.
unknowing
its on top of the fuel tank pump RACK.

if engine is tuned up,?
and power is low at wot,
i check fuel pressure live.(under varying engine loads)
if the pressure is out of spec, i get a new filter and PPR.
if pressures are in spec. dynamically.
i find out why the PCM is under-injecting.
ask how. its not hard.
(bad MAP?, , injector balance tests?)

Jul 16, 2015 | Jeep Cars & Trucks

2 Answers

Nissan v6 idle


looks like that either you do have an air mass not correct working,or the throttle body is too dirty and you have to clean it.Also check for any cracked, snapped vacuum hose.

Mar 11, 2014 | Nissan Cars & Trucks

1 Answer

1996 crown victoria misfiring loss of power under light to heavy acceleration, rough idle


The plug wires on this model year and prone to burn through, replace them all, do one at a time and always put them back in the factory wire looms they run through, that is very important, replace any you may break. Use high qyuailty oplug wuires foractory parts are preferred..

Jun 07, 2013 | 1996 Ford Crown Victoria

1 Answer

#3 and #7 misfire codes


Swapping coils between cylinders is a better solution than replacing them. This way if the misfire follows the coil you know the coil is bad. Lack of power under load usually suggest fuel starvation to me. I would change the fuel filter and then road test the car. Also if you had just filled up the tank when the misfires started, maybe you got a bad tank of gas. Sometimes right after a rain water gets churned up and gets into the pump, and consequently your fuel tank.

Dec 23, 2011 | Cars & Trucks

3 Answers

I got a 99 tahoe 5.7 vortec with multiple misfires under load/accelerating. So far Ive replaced; plugs, wires, cap n rotor, coil, egr valve, fuel filter, o2 sensors. Tested; vacuum, fuel pressure, OBD 2...


this is one of those situations that a professional diag would of saved you alot of money. Its possible you just got bad gas and your injectors are partially clogged. An 02 sensor would not give multible misfires. EGR would only misfire at idle if stuck partially open since its suppose to be open cruising. Fuel filter would give you a starvation issue but if the misfires happens at idle then the filter most likley is ok.
Data from a professional data scanner will store the conditions when the misfire occurs. Also for a chevy each cylinder will have a misfire counter and one can see the misfire happening as it happens. If its idling and misfiring and gets better as you rev it up most likely you have clogged injectors or a intake vacuum leak. You can test for a intake leak by spraying the intake area with water(idle will faulter if it draws water in), or use brake cleaner (idle will raise when fluid gets drawn in).

If no leaks are found I would do an injection service or at least add two bottles of techron to a full tank, drve till half a tank then top off again.

Also if the catalytic converter is clogged the backpressure could cause all sorts of misfire issues. Removing the two upfront 02 sensors and driving will indicate the exhaust is clogged or not. We put a pressure sensor in place of the 02 sensor. If the pressure is above 5psi this would indicate some blockage. It should be below 3psi at 2000 rpm. Also if you have K/N filter the oil from it will coat the maf sensor wires in time,, (always). You can remove the sensor and spray the wires with brake cleaner to clean. DO NOT touch them. They can be brittle. Look at the wires for color. They should be shiny silver. If its coated the PCM will not see the air volume or accurately see the air temperature. Without this information the PCM will not add enough fuel which will create a misfire.

Jul 07, 2010 | 1999 Chevrolet Tahoe

1 Answer

I am having ongoing problems with the truck miss firing and rough running. Timing is ok, replaced cap and rotor,coil. It still starts rough,idles rough and misses when at cruising speed,although it seems...


Misfire is a common driveability problem that may or may not be easy to diagnose, depending on the cause. A misfiring cylinder in a four-cylinder engine is, pardon the pun, hard to miss. The loss of 25% of the engine's power output is the equivalent of a horse trying to run on three legs. The engine may shake so badly at idle that it causes vibrations that can be felt in the steering wheel and throughout the vehicle. The engine also may be hard to start and may even stall at idle, depending on the accessory load (air conditioning, headlights and electric rear defroster, for example).

When misfire occurs, performance suffers along with fuel economy, emissions and idle quality. And, when a misfiring vehicle is subjected to an emissions test, it will usually fail because of the unusually high levels of hydrocarbons (HC) in the exhaust.

What causes a cylinder to misfire? Basically, it's one of three things: loss of spark; the air/fuel mixture is too far out of balance to ignite; or loss of compression. Loss of spark includes anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. Causes include worn, fouled or damaged spark plugs, bad spark plug wires or even a cracked distributor cap. A weak coil or excessive rotor gas inside a distributor would affect all cylinders, not just a single cylinder.

"Lean misfire" can occur when the air/fuel mixture is too lean (not enough gasoline in the mixture) to burn. This can be caused by a dirty, clogged or inoperative fuel injector; air leaks; or low fuel pressure because of a weak pump, restricted filter or leaky pressure regulator. Low fuel pressure would affect all cylinders rather than an individual cylinder, as would most air leaks. A leaky EGR valve can also have the same effect as an air leak.

Loss of compression means the cylinder loses most of its air/fuel mixture before it can be ignited. The most likely causes here are a leaky (burned) exhaust valve or a blown head gasket. If two adjacent cylinders are misfiring, it's likely the head gasket between them has failed. Also, if an engine is overheating or losing coolant, it's likely the head gasket is the culprit.

Intermittent misfires are the worst kind to diagnose because the misfire comes and goes depending on engine load or operating conditions. They seem to occur for no apparent reason. The engine may only misfire and run rough when cold but then smooth out as it warms up. Or, it may start and idle fine but then misfire or hesitate when it comes under load. Also, it may run fine most of the time but suddenly misfire or cut out for no apparent reason. Intermittent misfires can be a real challenge to diagnose, so let's start with a steady misfire in one cylinder before moving on to intermittent misfires.

Hope this help.

Mar 25, 2010 | 1989 GMC Sierra

2 Answers

Sonoma 2.2ltr misfires under load. have replaced;


Check the fuel pressure regulator, make sure it's working properly and also clean out the MAF sensor with MAFcleaner. it sounds like your having the engine go lean under load. Good luck

Nov 13, 2009 | 1998 Chevrolet S-10 Pickup

1 Answer

Chevy 3500 Express truck. fuel problem?


IF YOU GOT CYLINDER MISFIRE.OR OPEN FUEL INJECTOR.THAT WILL CAUSE THE PCM TO ENRICHEN FUEL MIXTURE.TO ADJUST TO DEAD CYLINDER.WHICH ACT AS A LARGE VACUUM LEAK.THATS WHY YOUR EXHAUST TAIL PIPES HAS A RAW FUEL SMELL AND WHITE SMOKES.

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2 Answers

1999 Dodge Ram 5.9L 4X4 not enough fuel


check the fuel filter and the EGR valve

May 07, 2009 | 1999 Dodge Ram

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