Engine Engine Wont Run Passed 4k Rpm

coyote1993 · Oct 15, 2017

Hi i am new on this site.
i have a 98 gt with a 2001 pi engine in it. I installed new timing chain guides and tentioners. The car is sluggish and it wont rev clean and stops reving at 4k rpm. Ive checked fuel pressure at idle and at WOT and it is within spec and deosnt drop off. I know the cam timing is correct I triple checked it. Do i need a tune? The car has non pi coil packs with a stock 98 computer. would this cause the issue? what am i missing?

trinity_gt · Oct 15, 2017

Got the firing order correct?

coyote1993 · Oct 16, 2017

trinity_gt said:
Got the firing order correct?

yes. i tooked it up amd it is wired just as a non pi should be with the 2 coil packs.

squeak93 · Oct 16, 2017

Its either a fuel or spark problem.

You do not need a tune although it would optimize it best. It will run just fine on a stock tune and the coil packs are fine as well.

Plug wires or fuel filter would be where I'd start.

coyote1993 · Oct 16, 2017

i already dud the filter i will try plugs and wires

Kurt G. · Nov 28, 2017

I worked on a non mustang and found a cam sensor messing up, would not rev above 3k. Check that out.

wmburns · Nov 28, 2017

Question. When it is running does it run smooth? Does it make power below 4k RPM's? Are there any DTC codes?

Double check that the motor grounding strap was installed between the left hand motor mount and the frame rail.

Double check that the alternator is putting out more than battery voltage. Battery voltage should be greater than 13.8 volts while the motor is running. Not a bad idea to perform a through review of the charging system. Note. A bad alternator diode can "cause" the cam sensor to appear to be bad.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

Do you have an infrared scanning thermometer? What I would like to know is IF there is a big temperature difference between the right and left exhaust manifolds.

Do you have an ODB2 scanner? I would like to know if the PCM is pulling timing at 4k RPM's. On some DTC codes the PCM will respond by dropping into a "limp in" mode. One of the ways the PCM protects the motor during limp in mode is by pulling timing. Other "possible" causes for limp in mode might be excessive coolant temperature (ECT).

Here's some information on an affordable Windows based ODB2 scanner.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

As others have said you don't have to have a tune to run this motor. It should run well enough to drive assuming everything else is OK. Likely there's something else "causing" your problems.

Sluggie24 · Nov 28, 2017

I've seen weak/bad coils cause the exact symptoms you are describing on many different cars.

coyote1993 · Nov 28, 2017

Kurt G. said:
I worked on a non mustang and found a cam sensor messing up, would not rev above 3k. Check that out.

I will check that

coyote1993 · Nov 28, 2017

wmburns said:
Question. When it is running does it run smooth? Does it make power below 4k RPM's? Are there any DTC codes?

Double check that the motor grounding strap was installed between the left hand motor mount and the frame rail.

Double check that the alternator is putting out more than battery voltage. Battery voltage should be greater than 13.8 volts while the motor is running. Not a bad idea to perform a through review of the charging system. Note. A bad alternator diode can "cause" the cam sensor to appear to be bad.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

Do you have an infrared scanning thermometer? What I would like to know is IF there is a big temperature difference between the right and left exhaust manifolds.

Do you have an ODB2 scanner? I would like to know if the PCM is pulling timing at 4k RPM's. On some DTC codes the PCM will respond by dropping into a "limp in" mode. One of the ways the PCM protects the motor during limp in mode is by pulling timing. Other "possible" causes for limp in mode might be excessive coolant temperature (ECT).

Here's some information on an affordable Windows based ODB2 scanner.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

As others have said you don't have to have a tune to run this motor. It should run well enough to drive assuming everything else is OK. Likely there's something else "causing" your problems.

I do have a scanner I will check these things thank you

coyote1993 · Nov 28, 2017

wmburns said:
Question. When it is running does it run smooth? Does it make power below 4k RPM's? Are there any DTC codes?

Double check that the motor grounding strap was installed between the left hand motor mount and the frame rail.

Double check that the alternator is putting out more than battery voltage. Battery voltage should be greater than 13.8 volts while the motor is running. Not a bad idea to perform a through review of the charging system. Note. A bad alternator diode can "cause" the cam sensor to appear to be bad.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

Do you have an infrared scanning thermometer? What I would like to know is IF there is a big temperature difference between the right and left exhaust manifolds.

Do you have an ODB2 scanner? I would like to know if the PCM is pulling timing at 4k RPM's. On some DTC codes the PCM will respond by dropping into a "limp in" mode. One of the ways the PCM protects the motor during limp in mode is by pulling timing. Other "possible" causes for limp in mode might be excessive coolant temperature (ECT).

Here's some information on an affordable Windows based ODB2 scanner.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

As others have said you don't have to have a tune to run this motor. It should run well enough to drive assuming everything else is OK. Likely there's something else "causing" your problems.

it makes power but it is sluggish and lags for about a second then comes to life and falls on its face like its out of fuel. it also pings really bad at any throttle position. from slight accel to wot

wmburns · Nov 28, 2017

coyote1993 said:
it also pings really bad at any throttle position.

From the Ford PC/ED "spark knock" chart 9.
>>
SYSTEM/COMPONENT REFERENCE (Section 5 Pinpoint Test unless noted)
Verify engine operates at normal temperature
Visual (refer to Symptom Index or Engine Cooling Section 303-03 of the Workshop Manual, to diagnose any cooling system concerns that are present).

Mass Air Flow (MAF) Sensor
:GO to DC25
Base Engine
:Engine System - General Information Section 303-00 of the Workshop Manual
Fuel Delivery System
:GO to HC1
Secondary Ignition System
:GO to JB1
PCV System
:GO to HG1
Engine Oil Quality
:Visual
Additional Testing
<<

Note that engine coolant temperature is top of the list.

One of the other "possible" causes could be related to base engine timing (replacement timing chains). Describe HOW the engine was timed when the chains were replaced. Because there's a possibility that the base engine timing has been advanced and that is what is causing the pinging.

Engine Engine Wont Run Passed 4k Rpm

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