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Erratic idle have a 1993 jaguar xj6 4.0. put a new set of catalytic converters on and the idle started going up and down. can not test on dyno because the rpms go up and down in the 1500 range

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  • Cars & Trucks Master
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Sounds like you may have a small exhaust leak. This will drive O2 sensors crazy trying to regulate the engine. You end up with an engine endlessly revving up and down.

Posted on Nov 19, 2013


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Posted on Jan 02, 2017

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SOURCE: 98 chevy 1500 loses power

sounds like an ECU of the chips is breaking down when the units warms up

Posted on Nov 04, 2008

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SOURCE: 1998 chvy 1500 loses power

check the intake gaskets. in the middle front and middle rear. If they are oily, it more than likely sucked part of the gasket in. When it warms up the leak gets bigger. The easy way to check is to get some carb cleaner and spray all around the intake while idling and warm. DO NOT SPRAY ANY EXHAUST PARTS , carb cleaner is combustible. The truck should stumble or even shut off when spraying with the carb cleaner if there is a leak.

Posted on May 03, 2009

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SOURCE: Integra revs RPMs when idling

idle air control motor or just a plain old vacuum leak

Posted on Jul 21, 2009

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SOURCE: 1993 mazda mx6 idles jumps up and down between

The butterfly at the air intake may be dirty. If at all possible remove the breathers leading to this and clean the butterly with carbuerator cleaner or something like it. There may be deposits and it is not breathing good.

Posted on Oct 09, 2009

  • 543 Answers

SOURCE: red hot catalytic converter, motor shaking, and no codes.

well you could have had a cat converter go bad before thats possible,either you now have a piece of the old broken cat stuck in the exhuast pipe,or you have what i think is a bad ignition module/coil pack and spark plugs causing a major misfire causing it to over heat and have no power,,,or its out of timing causing the same issue,,its odd it has no codes,no ses light,if its a bad coil its got a ses,,these are just a few ideas its too hard to tell without seeing the car

Posted on Oct 19, 2009

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I have a 1993 dodge dakota that will not run when I put it in gear. If I let it set for awhile (2-3 hours) it will start right up and idle for as long as I want without missing but as soon as I put it into...

Check fuel filter, relay, fuel pump, sometimes the pump will run, but still too weak to run an engine at speed or underload. If fuel pressure checks out to be fine, look for a clogged catalytic converter.

Dec 15, 2013 | 1993 Dodge Dakota

1 Answer

My 94 full size blazer starts and idles fine in park and in neutral. When I put the truck in gear and hit the gas, it'll start, then act like it wants to die. The Catalytic converter is off, I'

yes try getting the fuel pump pressure tested by a mechanic. the other thing it can be is the injectors are plugged try running some lucas fuel system cleaner.

Jan 19, 2013 | Chevrolet 1500 Cars & Trucks

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I have a 2002 Ford Escape. It ran perfectly until I took it for a car wash and it rained hard the next day. I then had rough idling, laboured acceleration and I threw a Code saying I was missing in 2 and...

I think someone gave you wrong information. You know what a rough idle and a misfire you just went through it. And you went through a emission test and passed. Here the thing about the emission test they do it 2 ways if you went on a dyno. The dyno loads the engine and pressurize the system. It looks for pressure failure,like sparkvoltage leaks,and like transmission pressure line and test its ability to maintain gear ratio at an approprate load. Then the dyno heats the vehicle now it looks for operating temperature and that all sensor are within fuel control and do not go out of range. Here the thing. 5000k and 4000k it takes that much to get it to cruising speed. and once there its okay. You are describing a transmission slip. And catalytic costing 4 thousand. From the dealer? If the catalytic are clog there is no way to get it to cruising speed , No youll loose power and the vehicle will keep slowing down. If the transmission is slipping it will slip in a variety of ways One way is what you described. It will 5000k and 4000k to get it to cruising speed then its okay. And not do highway speed , catalytic is about 1200. transmission are 4000k.Plus Ford tried to sue states that put the vehicle on dynos,due to the high trans failures(this is on going debate)

Apr 25, 2011 | Ford Escape Cars & Trucks

1 Answer

Idles but will not accelerate

Try checking your catalytic converter it may be clogged. You can cut it out and put a test pipe in to check it out.

Jul 20, 2010 | 1993 Toyota 4Runner

2 Answers

Where is the catalyst converter located

In the exhaust line...

NOTE:For component location, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION . For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Monitored & Set Conditions
Catalytic converter efficiency is monitored after engine warms up to 158°F (70°C), throttle has been open for 180 seconds at vehicle speed more than 18 MPH, with engine speed at 1200-1700 RPM and MAP vacuum 15-21 in. Hg. DTC will set in Powertrain Control Module (PCM) memory when PCM senses catalyst efficiency deteriorated to a predetermined value. Possible causes for DTC to set are: intermittent condition, exhaust leak, engine mechanical problem, defective catalytic converter or upstream Heated Oxygen Sensor (HO2S) is older than downstream HO2S.
NOTE:1/1 HO2S may also be referred to as an upstream oxygen sensor. On 2.4L, 1/1 HO2S is located on exhaust manifold flange. On 3.3L and 3.8L, 1/1 HO2S is located on right exhaust manifold flange (manifold closest to firewall).

NOTE:If any O2 sensor DTCs are set along with P0420, diagnose those DTCs before continuing with this test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .

Turn ignition on. Using scan tool, read DTCs. If Good Trip counter is displayed for DTC P0420 and displayed count is "0", go to next step. If Good Trip counter is not displayed for DTC P0420 or displayed count is not "0", go to step 7 .
Inspect catalytic converter for damage, discoloration caused by overheating and for converter coming apart internally. Replace catalytic converter as necessary. If catalytic converter is okay, go to next step.
Start engine and allow it to idle. Check for exhaust leaks between engine and 1/1 HO2S. Repair exhaust system as necessary. If exhaust system is okay, go to next step.
Check exhaust for excessive smoke caused by coolant entering combustion chambers or high oil consumption. If excessive smoke caused by coolant entering combustion chambers or high oil consumption does not exist, go to next step. If excessive smoke caused by coolant entering combustion chambers or high oil consumption exists, repair engine as necessary and replace catalytic converter.
NOTE:A new downstream HO2S used along with an aging upstream HO2S may cause DTC P0420 to set.

If downstream HO2S has been replaced without replacing upstream HO2S, replace upstream HO2S. If downstream HO2S has not been replaced recently or downstream HO2S has been replaced along with upstream HO2S, go to next step.
At this time, catalytic converter is assumed to be defective. Replace catalytic converter.
NOTE:A new downstream HO2S used along with an aging upstream HO2S may cause DTC P0420 to set. Review vehicle repair history and repair as necessary.

Conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review Freeze Frame data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. If no problems are indicated, test is complete.

Good luck.

Oct 14, 2009 | 2000 Chrysler Town & Country

1 Answer

1993 buick park ave will not change gears

Have your Catalytic Converter checked for free flow, (if it is stopped up with calcification from unspent fuel, then the car will have trouble moving at all). A tell tale sign of oncoming Catalytic Converter problems is the overdrive balking or wanting to hesitate, when the transmission is in overdrive the vehicle is running at its lowest r.p.m. and so like at idle it will stumble or hesitate, or cut the engine altogeter, for the motor has to be able to exhale, to exhaust its combustion gases, in order to run properly, stopped up catalytic converters are a big problem with this car.

Apr 16, 2009 | 1993 Buick Park Avenue

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