Question about 1988 Isuzu Trooper 2 Door

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Will not idle at proper rpm

Engine will not return to idle ,currently idles at 3000 rpm. does not appear to be a linkage tank fuel pump is new 2.6L engine, manual tranny

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Try squeezing the fleixible fuel line before it gets into the fuel rail with the appropriate tool and see if the RPMs drop if they do either the pressure relief valve has failed or the fuel return line is blocked.Obviously you dont completely squeeze the line shut but only that you are taking some of the pressure out of the fuel rail allow enough fuel through to keep vehicle running.Its a cheap way to eliminate a potential cause for your problem.Excess pressure could be over powering the injectors.Are the injectors in a good servicable condition?

Posted on Nov 02, 2008


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My car Chery QQ 0.8 rpm go from 1000 rpm to 3000 rpm and stays there

Most likely the fuel filter is contained in the fuel sender assembly inside the fuel tank.

Check again on your diagnostic report. The error code P0505 is the idle air. If the characteristics of the current problem was resolved by the replacement of the idle air control valve I would assume that either the connection is not reliable or the new unit has also become defective.

From your description of the problem you had changed the idle air control valve and the problem was corrected for a while. The error code indicates that the problem has reoccurred. Check the warranty on the replacement part and return for replacement. It is likely the replacement has failed.
P0505 code is an indication that your iac control motor is defective
26150635-emweptctsl5vxsoydbirzle5-2-0.jpg Hope this has helped?

Apr 03, 2016 | Cars & Trucks

1 Answer

1999 dodge intrepid idles at 3000 rpm

Check your I A C motor (idle air control motor) Check all your hoses and tubes leading to and from. Check the throttle linkage itself to make sure nothing is obstructing it from returning to normal rpm,

Apr 01, 2012 | 1999 Dodge Intrepid

1 Answer

Code p1128 weak mixture lose power on inclines engine light on melts spark plugs vehicle hyundia accent 2001

Go to and register your vehicle by VIN #..
you'll then have access to wiring diagrams, shop manuals,
service bulletins, illustrations, etc. To diagnose a 2000 or 2001 1.5L Accent Diagnostic Trouble Code (DTC) P1128 (FUEL SYSTEM LEAN -- PART LOAD), check the following:
  • Check the intake system for air leaks.
  • Check that the Mass Air Flow (MAF) Sensor (P/N 28164-22610) operation meets the specifications listed below. If the MAF sensor output is significantly lower than the reference value (10% or more), then replace the MAF sensor.
Table 1: Using the Hi-Scan Pro in the Hyundai Diagnostic Menus Current Data Screen TPS (%) 0
MAF (kg/h) 10
Table 2: Using the Hi-Scan Pro in the OBD-II Menus Current Data Screen TPS (%) 0
MAF (g/h) 2.8


Table 3: Using the Hi-Scan Pro in the Hyundai Diagnostic Menus Current Data Screen TPS (%) 0
MAF (kg/h) 9.5
Table 4: Using the Hi-Scan Pro in the OBD-II Menus Current Data Screen TPS (%) 0
MAF (g/h) 2.5

Jun 26, 2011 | Hyundai Accent Cars & Trucks

1 Answer

I have a 1992 E350 motorhome with a 7.5 in it. I just had to replace the fuel pump. After replacing the pump it idles rough and runs rich. I did pick up an engine light and after getting the codes...

There is a few options but first I am hoping with your fuel pump replacement that you replaced the fuel filter if not do it first.
next have you checked you throttle body idle speed control device... See below on diagnostics
The curb and fast idle speeds are controlled by the Engine Control Assembly (ECA) and the Idle Speed Control Bypass Air Valve (ISC-BPA) . The ISC-BPA valve is not adjustable. A large increase or decrease in closed plate airflow from the calibrated level will not allow this device to control the speed.
The idle speed setting procedure has been revised considerably to reflect the expanded application of the Self-Test idle speed options and because the throttle body incorporates an orifice in the throttle plate to control idle airflow as part of the sludge tolerant design.

Throttle bodies with sludge tolerant design are clearly identified with a Yellow/Black decal. This decal warns that the throttle plate stop screw must not be adjusted counterclockwise (backed off), as this will not reduce the engine speed but may cause the throttle plate to stick in the bore. Backing out the screw may be required if the throttle body has been previously serviced (a plug in the throttle plate orifice may be present) or the plate stop screw tampered with (TPS Self-Test output out of range). The decal also warns that the throttle body must NOT be cleaned inside the bore, as this cleaning will impair the sensitive coating. The sludge accumulation will not affect the idle air flow. The cleaning procedure for the ISC-BPA still applies.

A change in idle airflow can occur not only at the throttle body but other areas as well. You should enter the idle speed procedure only after other possible causes in the following areas are eliminated.
  • Contamination within the idle speed control device
  • Lack of fuel system control (excessively rich or lean)
  • Throttle sticking or binding
  • Engine not reaching operating temperature
  • Incorrect ignition timing
  • Incorrect or clogged PCV system
  • Vacuum leaks (intake manifold, vacuum hoses, vacuum reservoirs, power brake booster etc.

  • Transmission is in PARK (A/T), or NEUTRAL (M/T)
  • Parking brake is applied (automatic brake disconnected where applicable)
  • Wheels blocked
  • Engine at operating temperature
  • Proper fuel pressure and no exhaust smoke
  • Correct and clean PCV system
  • Heater, A/C, and other accessories OFF
  • Ignition timing is set to specification
  • EEC-IV diagnostics have been performed and vehicle malfunction indicated service output codes have been resolved.
With the engine OFF, connect a tachometer, according to manufacturer's instructions. Disconnect the negative (-) terminal of the battery for 5 minutes, then reconnect it.
START the engine and let stabilize for two minutes. Goose the accelerator and let the engine return to idle. Lightly depress and release the accelerator, then let the engine idle.
If the engine is not idling properly, turn the engine OFF, and proceed with this procedure.
Disconnect Idle Speed Control Air Bypass Solenoid.
START and RUN the engine at 2500 rpm for 30 seconds.
Place the transmission in PARK (A/T), or NEUTRAL (M/T).
Using a tachometer, verify the idle speed is at 650 +/-150 rpm.

NOTE: A plug in the throttle body orifice will decrease idle rpm. Where as an orifice without a plug will increase idle rpm. Orifice plugs and installation tools are available in service kit # FOPZ-9F652-A.

  1. DO NOT clean the throttle body, check the plate orifice plug.
    • If there is no plug, turn the screw clockwise to the desired rpm.
    • If there is a plug from previous service, remove the plug, then adjust the screw in either direction as required. Screw must be in contact with the lever pad after adjustment.
  1. Turn the engine OFF.
  2. Disconnect air cleaner hose.
  3. Temporarily block the orifice in the throttle plate with tape. If the orifice already has a plug from previous service proceed to Step (e).
  4. RESTART the engine. Check the idle speed, using a tachometer. NOTE: On vehicles with Mass Air Flow Sensors, reconnect the air intake duct hose prior to rechecking the rpm. If the engine stalls, crack open the throttle plate stop screw, but DO NOT over adjust.
  5. If rpm continues to be fast, perform KOEO Self-Test.
    • If TPS output code is within range, remove tape from throttle body and check for other possible causes.
    • If TPS output is out of range, adjust screw for proper TPS code. Lever must be in contact with the screw.
    • If rpm is still fast, terminate the procedure and check for other possible causes.
  1. If rpm drops to 650 rpm or lower, or the engine stalls, turn the engine OFF, disconnect the air cleaner hose, and remove the tape from throttle plate.
  2. Install an orifice plug with proper color code according to the throttle plate orifice size.
  3. Reconnect the air cleaner hose. START the engine, and check the idle rpm using a tachometer. Turn the throttle plate stop screw clockwise until an idle speed of 650 +/- 25 rpm is achieved. NOTE: DO NOT turn the plate stop screw counterclockwise. This may cause the throttle plate to stick at idle.
Run the KOEO Self-Test for proper TPS code output.
Reconnect the Idle Speed Control Air Bypass Solenoid. Verify the throttle is not sticking in the bore, and the linkage is not preventing throttle from closing.
START the engine and idle for two minutes. Goose the accelerator and let the engine return to idle. Lightly depress and release the accelerator, then let engine idle.


Remove air inlet tube(s) from throttle body.
dak408_16.gif STEP 2
Select the proper color plug by using the Go/No-Go gauge pegs, included in the service kit (FOPZ-9F652-A).
Starting with the largest diameter gauge peg, attempt to insert through the throttle plate orifice.
If the gauge peg goes through the orifice, use the corresponding color plug.
If the gauge peg does not go through, proceed with the next smaller gauge peg for Go/No-Go Test.
NOTE: It is important that the largest Go/No-Go combination is used to determine the proper plug size.
If the smallest gauge peg does not go through the orifice, use the reamer bit and handle included with the service kit to enlarge the plate orifice. Wipe bearing grease on both sides of the plate orifice and on the reamer bit to hold the brass chips. After reaming, wipe plate clean and then return to Step 3 to determine the proper plug size.
Using the installation tool from the service kit, push the plug into the orifice until bottoming out at the throttle plate.
Open and snap closed the throttle several times to verify proper plug retention.
Reconnect the air inlet tube(s).
Reset idle rpm per engine requirement using the throttle plate stop screw.

Hope this helps

Nov 11, 2010 | 1992 Ford F250

1 Answer

Engine is dying on idle

quick test , replace a piece of the fuel line with a clear plastic one, chaeck for air bubbles especially with less than half tank

Jul 28, 2010 | 1990 Isuzu Trooper

1 Answer

When starting, engine will rev up to 3000 rpm then will die. but you can keep it running if you keep it revved up above 3000 rpm

Things to look for: Could be your intake manifold gasket, throttle position sensor, vacuum hoses, throttle body gasket, idle screw, fuel pump, fuel filter, fuel pressure regulator, or maybe you have a split in your gas tank or fuel line(s) that is messing with your fuel pressure. See if you smell gas back near the driver's side rear wheel.

Good luck, those are things I would search for, I can't promise anything, could be a number of things. You should have a check engine light on.

May 23, 2010 | 1993 Honda Accord

3 Answers

High RPM between shifts or at idle after driving/ warm engine

Clean the choke and linkage around the air cleaner again.

You are on the right track.

I will give ALL the intake manifold bolts a 1/6 turn....just to rule out leaky intake manifold gasket.

Check for loose or leaky vacuum hose.

Since you truck is 1987. I will replace all small vacuum hoses.

Change one at at time.

Change the fuel filter
Test fuel pressure
Check the ohm specification on the coil.
If the wires are over 3 years old then replace it
Check and clean contacts
Make sure the wires are not cross.

Do a good carb. cleaning and use Chevron gas for one tank full. Do some high RPM highway ran and see does it improve.

Aug 23, 2009 | 1987 Toyota Pickup

1 Answer

Engine starts,reaches high rpm,then slowly returns to a rough idle, misses badly,no backfire,surges as if searching/adjusting air/ fuel/est,timing light shows mark constantly changing/erratic,engine then...

Vacuum leaks. Check all hoses and intake bolts. Leaking EGR or plugged PCV valve. Air filter plugged. Leaking head gasket. Worn timing chain. Camshaft lobes worn. Valves burned or leaking. Fuel idle control system or sensor. Good luck!

Apr 18, 2009 | 1991 Chevrolet Camaro

1 Answer

Eratic idling and misfiring under pressure

confirm that the fuel pump delivers the proper pressure to the injectors

Mar 08, 2009 | 2000 Volkswagen Jetta TDI

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