Engine 1987 5.0 Sputtering & Jerking Please Help

Rauchbauer · Jan 15, 2023

First I wanna say I have 1987 LTD Crown Victoria with a 5.0 (I know it's not a mustang but figured somebody would still have some insight). I've been dealing with a sputtering and jerking in my car. It does it whether it's idling, accelerating, or up to highway speed but it is definitely worse under load. It is an intermittent problem but tonight was the worst it's done it. Here's what I've replaced so far:
-Spark plugs
-Wires
-Cap
-Rotor
-Ignition Coil
-TPS sensor
-ICM on the Distributor
I have an aftermarket K&N air intake and dual exhaust with the downstream cats removed. EGR valve is unplugged and capped off. I have ran it this way for a long time with no issues and great performance. I also 'tested' the MAP sensor tonight. Started the car and disconnected the vacuum line with it running and the engine killed so I know it's not stuck open/closed. I ran a KOER test and the codes I received were DTC 31, DTC 94, & DTC 44 which all point to emissions I believe. (I should mention I had a TPS code that has gone away since I replaced it but the car is still running the same). My next go to would be the pick up coil in the distributor, vacuum leak, or a fuel issue. Here's the weird part; during the KOER test the vehicle did not sputter once and it ran completely fine. As soon as the test was complete it began sputtering/jerking again, so would that mean it's something ignition/electrical? My gut tells me to shotgun the pick up coil and look at the distributor. Any insight would be helpful. I've already thrown quite a few parts at it and figured I'd check here first before I keep replacing stuff.

90sickfox · Jan 15, 2023

If I were you I'd check fuel pressure.

Rauchbauer · Jan 16, 2023

I’ll try to borrow a fuel pressure gauge tonight. I didn’t mention above but I’ve been getting a check engine light when decelerating and coming to a stop. That could possibly just be the iac acting up though.

Rauchbauer · Jan 16, 2023

90sickfox said:
If I were you I'd check fuel pressure.

Bought a gauge at Harbor Freight for $30. I'll check it tonight. Any idea what the pressure should be?

General karthief · Jan 16, 2023

32 -34 psi at idle, 42-4 key on engine off

Rauchbauer · Jan 16, 2023

Here's my results from the pressure test:

Key On: 38psi and it leaked down to 0psi in 60 seconds.
Engine Running: 32psi
Rev Engine: 32psi with less than a variation of 5-10 psi
Remove Vacuum While Running: 42psi
Key Off: Leak down instant.

When I got home the car had been sitting 24 hours and it took a little longer to turn over and start. I'm not a professional but since it failed the leak down test does that mean it needs a fuel pump?

90sickfox · Jan 16, 2023

The fuel pump usually has a drain back valve that's internal. That will usually give a hard start but not hesitation.

Have you replaced the fuel filter ? If you pull it off shake it around covering both ends with your fingers. Dump it in a container with the end that went to the pump facing down. Should give you a good view of what the tank innards look like.

There are two 10 pin connectors right at the neck of the upper intake. They can get dirty and loose causing all types of issues. In the mustang world we call them the salt and pepper shakers. The red insert pops out so you can use a small screw driver or pick to tighten the female ends up a little. Electrical parts cleaner will help cleaning the old dielectric grease up. Add new dielectric grease after cleaning. Technically, it's the fuel injector harness.

Another thing to check is the engine temperature sensor. It's in a pipe right by the distributor. The computer uses this sensor to adjust fuel and go into closed loop.

I had a couple of those Crown Victoria's. With these cars getting old it could be an ECU thing. Ecuexchange.com should be able to rebuild your computer. If you plan on keeping the car its completely worth it whether it fixes the issues or not. Atleast you'll know you have a good foundation.

General karthief · Jan 17, 2023

As usual, I left out an important item pull the vacuum line off the fuel pump regulator, if you can smell fuel in the vacuum line the regulator is bad, prolly not your problem but good to check.
I would check the ignition switch, not the key switch on the column but the electrical switch, on the mustang it is under the dash and will cause issues like you describe, I would think it is also under the dash mounted on the column.

Rauchbauer · Jan 17, 2023

90sickfox said:
There are two 10 pin connectors right at the neck of the upper intake. They can get dirty and loose causing all types of issues. In the mustang world we call them the salt and pepper shakers. The red insert pops out so you can use a small screw driver or pick to tighten the female ends up a little. Electrical parts cleaner will help cleaning the old dielectric grease up. Add new dielectric grease after cleaning. Technically, it's the fuel injector harness.

Just to eliminate a few things ignition switch was replaced a year ago and there was no indication of gas in the vacuum. Appreciate your response. So your thoughts are ecu, temp sensor, fuel filter to start off? Also was curious about this section you wrote. Could you clarify a little more, are you talking air intake or manifold?

90sickfox · Jan 17, 2023

Engine temp sensor

10 pin connectors

90sickfox · Jan 17, 2023

It would be best to search for a way to test the sensors before replacement with a multimeter. A fuel filter is just basic maintenance. Did fuel pressure drop when revving the car ?

The computer 99.9% needs repair. The capacitors have a shelf life of about 20yrs. Our cars are past that for sure.

It can get expensive just replacing parts.

Rauchbauer · Jan 18, 2023

Fuel pressure does not drop when revving. It stays consistent. Checked the 10 pin connectors and they look good. The car had a tune up about 10 years ago and I could see there was fresh grease on them and one of four of the connector clips was broken so somebody has already maintanced at them. Between the temp sensor and fuel filter it's only $40 so I'm gonna go ahead and replace those and I will provide an update once I have. Just to circle back the distributor stator/pickup coil has not been replaced yet. Do you think that's worth looking into? I figure I'll start with the two items listed above first. Could you verify I'm on the right website for ECU:

Ford Mustang 5.0 A9L A9P C3W A3M X3Z ECU Repair Service

Ford Mustang 5.0 A9L A9P C3W A3M X3Z ECUEngine Computer Repair ServicePlease fill out the R&R form here once you've placed your order.A Trusted Product with LIFETIME WARRANTY QUICK TURN AROUND TIMEDomestic and International Shipping available! Our Team is Available Monday - Friday 9am to 5pm...

www.theecuexchange.com

I've never had to replace/rebuild one before.

Rauchbauer · Jan 18, 2023

Just called the shop that my dad had it serviced at and cruised through the service record:

Pump & Filter were replaced about 30,000 miles ago
They already replaced the ICM on the distributor (Due to no spark) and had pulled the distributor to do so. I've attached pictures of the one I replaced and what's interesting is you can see the one I pulled off looks like it got hot in a matter of 30,000 miles. It really makes me lean towards an ignition problem rather than fuel. Let me know your thoughts. I pulled the distributor cap and took a picture on the inside. It almost looks to me like I should replace the stator/pickup coil first.

AeroCoupe · Jan 19, 2023

That is the correct place to have the ECU rebuilt.

If you are going to replace the TFI module then you need to find a FoMoCo unit and not an aftermarket.

More Information for MOTORCRAFT DY1284

Rauchbauer · Jan 19, 2023

AeroCoupe said:
If you are going to replace the TFI module then you need to find a FoMoCo unit and not an aftermarket.

You're the second one to say that. I'm not taking any chances so I just ordered the TFI from Rock Auto. I did not realize they had OEM thanks for the link. I'll check with the ECU company tomorrow. I'm getting tired of working on this thing and throwing money at it Any idea where the ECU is located?

AeroCoupe · Jan 19, 2023

They are typically in the passenger kick panel but not sure on the CV.

Have you seen this site:

Crownvic.net | Forums powered by UBB.threads™

www.crownvic.net

Was on there a bit when researching the CV front suspension for my F100. Lots of good info.

Rauchbauer · Jan 24, 2023

Just going to post a summary and recap on where I'm at with this:

1987 LTD Crown Victoria with a 5.0
I've been dealing with a sputtering and jerking in my car. It does it whether it's idling, accelerating, or up to highway speed but it is definitely worse under load. I have an aftermarket K&N air intake and dual exhaust with the downstream cats removed. EGR valve is unplugged and capped off. I have ran it this way for a long time with no issues and great performance. It also does have a hole in the left muffler.

Ford dealership replaced the following:
ICM, Pump, & Filter were replaced about 30,000 miles ago

Here's what I've replaced so far:
Spark Plugs, Wires, Cap, Rotor, Ignition Coil, TPS sensor, ICM on the Distributor (Installed aftermarket), Temp Sensor, & MAF Sensor.

Here’s my results from the KOER test:
DTC 31, DTC 94, & DTC 44
I had a TPS code that has gone away since I replaced it but the car is still running the same.

Here's my results from the fuel pressure test:
Key On: 38psi and it leaked down to 0psi in 60 seconds.
Engine Running: 32psi
Rev Engine: 32psi with less than a variation of 5-10 psi
Remove Vacuum While Running: 42psi
Key Off: Leak down instant.
Just to eliminate a few things ignition switch was replaced a year ago and there was no indication of gas in the vacuum.

I have a new fuel filter, ICM (OEM), and temp sensor (I broke the connector installing the last one). ECU has not been replaced yet and I have not checked timing either. I'm going to do the ICM and temp sensor tomorrow and if that doesn't do it I'll be looking at the fuel filter, ecu, and timing next.

KRUISR · Jan 24, 2023

Not sure if it applies to a Crown Vic, but did you do a base idle reset after changing those parts?

Rauchbauer · Feb 1, 2023

I have not yet but I have adjusted it by ear to where it runs smooth. Not sure the correct way to set it other than listening to the engine. It's been cold out so I haven't worked on the car in a while. It's supposed to be warm this weekend so I'll be replacing the fuel filter. Does this vehicle have an O2 sensor and could that be the problem? I was gonna look when I'm under the car this weekend. One of the codes referenced air/fuel ratio problem, rich fuel if I recall.

KRUISR · Feb 1, 2023

O2 sensor can definitely affect the air/fuel ratio.

Base Idle Reset is much more than just adjusting idle by ear. It starts with setting an idle and then a process for the PCM to learn how much to adjust things to get the correct idle.

Engine 1987 5.0 Sputtering & Jerking Please Help

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