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1988 Ford Crown Victoria stumbling, stalling, severe ping

Tiny
R. HELZER
  • MEMBER
  • 1988 FORD CROWN VICTORIA
  • V8
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
1988 Ford is in good condition, well maintained. It has developed a myriad of symptoms over time. They are INTERMITTENT and they are as follows:
>Sometimes engine stalls after startup.
>Engine stumbles and misses at low speeds ~30 - 35 MPH but will respond to stepping on throttle more but pings.
>Poor fuel economy about 30 - 40% below normal.
>If the problem occurs when pulling a slight hill, the engine will ping severely.
• Corrective action taken so far within past month.
New fuel pump (twice) fuel rail pressure is normal.
New fuel filter.
New EGR Valve
New EGR Position Sensor
New EGR Vacuum Regulator (EVR)
Vacuum leaks found and fixed
New spark plugs (correct Autolites)
Ignition timing checked and corrected (was 7 ° too advanced)
Plug wires, cap and rotor replaced 40,000 miles ago.
Catalytic converters removed and inspected and are GOOD.
The engine does not burn oil and does not make any strange noises.
There are no exhaust gases in the cooling system. (No leaky head gaskets).
Removing the vacuum line from the EGR valve and plugging the hose seems to alleviate the problem if it is occurring. If we put the hose back on the EGR, the problem will soon return. Note that the EGR, EGR position sensor, and EVR are all NEW as of one day ago and the old parts were confirmed bad, sticking, or erratic.

These problems will occur anytime, and for sure will happen after driving no more than five miles, and are getting worse as time goes on.

BUT when the problems are not there it runs perfectly with plenty of power.
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Friday, September 11th, 2009 AT 4:25 PM

13 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,355 POSTS
Has anyone checked the knock sensor? Is will adjust the timing to a point where it just is ready to begin to ping but stop it before it begins.
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Friday, September 11th, 2009 AT 10:06 PM
Tiny
R. HELZER
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  • 5 POSTS
It is a 5 Liter MPFI engine and as far as I know this model doesn't have a knock sensor. I think they started putting them in the 1992 model year.
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Friday, September 11th, 2009 AT 10:11 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,355 POSTS
That is what I thought too, but check out this web page. It has one for your car.

https://www.2carpros.com/articles/mitchell1eautorepair-car-repair-manuals
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Friday, September 11th, 2009 AT 10:17 PM
Tiny
R. HELZER
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  • 5 POSTS
I did finally find the knock sensor listed at the suggested web site, but I still think that they only use them in the 4 cyl and the 3.0 V6 in the 1988 year models.

I checked with my local parts house and they do not list a knock sensor for a 1988, 5 Liter engine.
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Saturday, September 12th, 2009 AT 4:40 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,355 POSTS
THat is interesting. I will double check. I believe the 5.8L was an option even though I have never seen one. Maybe it's for that. However, I punched in it's a 5.0L.
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Saturday, September 12th, 2009 AT 11:32 AM
Tiny
R. HELZER
  • MEMBER
  • 5 POSTS
I also put in that it is a 5.0 Liter and found the same thing you did, but that engine doesn't have a knock sensor.
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Saturday, September 12th, 2009 AT 12:01 PM
Tiny
R. HELZER
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  • 5 POSTS
No further action required. We found the problem ourselves and it's fixed now. It was a broken valve spring. Thanks for all of your help 2CarPros is the best site ever!
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Sunday, September 13th, 2009 AT 11:03 AM
Tiny
T6166AS
  • MEMBER
  • 2 POSTS
  • 1999 FORD CROWN VICTORIA
  • V8
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
Engine Performance problem
1999 Ford Crown Victoria V8 Two Wheel Drive Automatic 160000 miles

My car has been running lean and I have changed MAF sensor, changed intake manifold and got injectors cleaned. I got p0171 and p0174 DTC couple of days ago. Fuel pressure has been tested by the mechanic and he says it is okay. I hooked up scan tool and saw that MAF shows reading of 4.2 lb/min at 2500 RPM when it should show only 2.1 according to ford service manual. Car jerks at each gear change and gas mileage is awful. Furthermore, car gives a heavy noise at slight acceleration (as if I am towing a trailer). The calculated laod value at idle is 35% and shoots to 80%+ while driving.
I also got exhaust checked by 3 different shops and they say it is all fine. Car has poor acceleration when hot and pings excessively.

Do not know what to do next?
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Friday, February 24th, 2017 AT 2:59 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,355 POSTS
Have you checked timing?
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Friday, February 24th, 2017 AT 2:59 PM (Merged)
Tiny
T6166AS
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You cannot adjust timing on these cars, they are controlled by PCM.
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Friday, February 24th, 2017 AT 2:59 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,355 POSTS
Yes, I know that. However, are you able to use a timing light to see if it is firing at the correct time? Also, have you checked the knock sensor? The pinging noise you are getting leads me to believe there is either an ignition timing problem or it is extremely carboned up. The knock sensor adjust ignition timing to the point right before it starts to ping to maximize engine performance. If not working properly, it can change the ignition timing too.
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-2
Friday, February 24th, 2017 AT 2:59 PM (Merged)
Tiny
CROWNVIC99
  • MEMBER
  • 1 POST
  • 1999 FORD CROWN VICTORIA
Greetings to all. Have a 99 CV w/ 155k miles, 4.6 that insists on nothing less than 93 octane. Anything less you will be met with a lot of heavy spark knock at partial throttle. Had been ok at 89 octane but no more. What I've done so far is: replace plugs, pull OBDC codes (none found), replace EGR & clean/decarbon throttle body (not much carbon), getting good EGR exh. Gas flow - (tested), sea foamed, replace MAF/air filter, PCM re-flashed at dealer - no change; however there's now a notable misfire while cruising (not the torqueconv 'shudder'). Not sure if O2 sensors have ever been replaced (had car since 97k miles). Also while at cruise/accel it seems to be 'holding back' - can the catcons be blocked? Any help will be most appreciated - many thanks!
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Friday, February 24th, 2017 AT 2:59 PM (Merged)
Tiny
TOBYU
  • MEMBER
  • 89 POSTS
I think you have two separate issues.
THe pinging is one and the missing has probably been caused accidentally by trying to fix the pinging.

The holding back you feel is probably just lower power from the miss. If you have one cylinder not firing. You have at least 12.5 percent loss. Probably more due to parasitic drag of a now power producint piston assembly rotating.
Your cats are probably fine. When the fords go out. They codes 0420-0430. The whole catalyst below threshold code thing. They rarely ever plug up.

Most 4.6s will do well without most noticable ping on 89. You said it used to now it needs 93. Unless your got a bunch of bad gas. It sounds like carbon build up or injector clogging spray pattern or low fuel pressure when the injectors fire.
I like sea foam too.
For decarboning. Plain old water will do the trick.
You need to run at about 1500 rpms and get enough water in there to steam clean the tops of pistons and the combustion chamber.
A pump up garden sprayer works great.
You can just pour water in, but a spray is safer.
It is possible to due damage (hydrolock) if you dump in too much water too fast.
I would run about a gallon through at medium rate. It will bog down and slow down engine and make funny noises in the plenum but don't stall it out.
Then go drive it and kick it down a couple of times from 25 MPH so it will downshift to 1st gear to blow it out good.

For the miss cancel out cylinders to find the one that's not putting out power. You can unhook the wires to the injectors one at a time or pull plug wires one at a time( use glove to avoid shocking)
I bet you have a bad spark plug.I have seen it in a 4.6 town car and a 4.9 Explorer recently.

O2 sensors will not cause a miss at all.
THe town cars have a "octane adjust" short connector you remove to stop pinging. It works. And my mileage went up with it removed.
I think the CV has it too. Should be on the drivers side under hood near brake booster. Gray plastic shunt I thik they call it.
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Friday, February 24th, 2017 AT 2:59 PM (Merged)

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