Engine Hesitates and surges

Has truck been checked for trouble codes? will MAP sensor hold vacuum?

Here are two guides to help us get started.

https://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

and

https://www.2carpros.com/articles/engine-hesitates

Please let us know what happens.

Haven't checked to see if the MAP will hold a vacuum yet but will do that right now. I'll give the booster valve a check as well.

OK, booster valve works as advertised and MAP will hold a vacuum. Also, no codes.

Did you get a code 11 or 111?

I checked the codes a few weeks ago and the only abnormal code I got was for the EGR position sensor which I then replaced and the code cleared. If I recall, I did get a 111 code.

Mind checking again we need a clue

Good to go. I'll check it again and get back with you in a couple hours.

Yep, got a 111.

Well out of ideas myself without being there. Really fits vacuum leak try removing EGR vacuum see if that helps. Have gone around intake spraying Carb cleaner to find leak?

Sure have. No indication of a leak. I think I've tried the EGR vacuum but I'll try that again to make sure. Any idea of what sensors come in to play when the computer goes in to closed loop? Thanks for your help!

Every sensor comes on line to control timing,fuel ect.and a code would set. Try this unplug IAC what happens to idle and surge?

Sounds good. I'll give that a shot.

With the IAC disconnected you have to keep the throttle open to idle. No change in surging. With EGR vacuum disconnected and plugged, no diff in surging and you get a check engine light. I concur that this seems like a vacuum leak issue but the system is completely tight. Actually I've never seen one this tight on a vehicle this old so I was really surprised. Doesn't sound like one but do think there might be a compression issue? Note that this truck sat for about two years until last fall. I purchaced it from the guy that bought it from the guy who let it sit.

Maybe a valve seating issue. Hook up a vacuum guage to intake. is vacuum steady at idle 15+? or does it flicker in relation to idle?

Great idea! Unfortunately steady at 18 at idle. Varys with engine RPM. Drops about 8 when the throttle is pressed then goes back up to 20 or so depending on RPM.

Where cam and crank sensores tested /replaced? has initial timing been checked? is it stable and does it advance with RPM incresce?

Haven't tested the cam or crank sensors. Timing is 10*btdc and advances with the throttle. They don't show either one at NAPA but I'll keep searching for them as well as testing procedures.

Doc had similar sorta issues with wife's Escape

Reckon my symptoms are sorta the same as his?

I had input from here also....ended differently

Disregard all of this, if we're not on the same country road

Thought I'd sling it out there, for observation anyway....open for any questions with mine....hope it's simpler than mine!

Pasting

Went thru same deal w/ '03 Ford Escape 3.0 V-6

Repetitive, fast hesitations (stumbles), lasting 1-2 seconds, varied in how far the "sets" were apart, it was more evident climbing a incline, while slowly administering gas....random or none on level ground......Every now and again at idle, but very seldom.

---No codes --- (cleaned 1st, and/ or replaced the following

New Plugs............then "genuine plugs".....Bah-Hum-bug!!!, nothing wrong with the other new ones, I just installed!

Boots and springs

air filter

MAF

EGR

A new IAC for Sheets & Giggles!

Mega Vacuum leak search several times.

Fought with wife many times over situation, 2+ months!

I really hated taking off the "Plenum" so many times to access the other 3 cylinders

Each part seem to fix it for a day or two....I did not mind replacing the suggested parts, as I am all for "PM" and she's got 100,000 miles on her rig.

The final cure was #3 misfiring (lucked into the correct cylinder) I was gonna swap a new coil pack down the line, till it stopped

#3 was the ticket!

I had tried to get the Technical school to ride me with their portable machine---things did not work out, with their schedule.

I went to a salvage yard to get a used pack ($10) to swap around, then buy a new one if solved the problem.

So happened, the salvage yard guy had a machine, in a stored code, it said #3 had misfired.....My little scanner could not tell me that!

Runs perfect now, with the New $79 Coil Pack!

Always stick with a Jeep CJ, You can diagnose them, as you hear 'em drive by!

The Medic

My bad that year did not use cam/crank sensor. When you state replaced everything in ignition was coil replaced?
OK just talked with a Frien who is Ford Tech said that plug wire miss routing will cause miss and surge see diagrams route this way.
If 7-8 and 2-4 routed next to each other surge will happen.

Medic,
Thanks for the advice. At this point I'd believe there's an EMI feedback signal from the Space Shuttle comm system causing my problem! :) Don't have a coil pack like you described. Got them on my wife's Volve though so I'm familiar with what you're speaking of.

Double checked the routing and it's as per the diagram. It's strange that this happens when in closed loop but is good the few minutes while it's in open loop.

I knew mine had the packs and yours did not---Thought the mis-fires and the "Symptoms" might steer you towards the coil or related.

Docfixit--has some great info there, with the diagrams, It does sorta seem sorta dumb that the spark would jump like that.....In older rigs like I'm used to, the wires could be hanging any which-away,pinched twisted, or deteriorated for 30 years, and they would work like when they were 1st installed!

Doc, reckon truck runnin', hood up, pitch black garage might shed some "Light" on the problem?

Sorry I could not be of any more help, but I will continue to watch from over here, behind your tool box, while the both of you continue, so I can learn too!

The Medic

Thanks again for the input Medic. I know what you mean about the older rigs. I remember my 67 LTD I had in highschool. Still did 120 with a blown head gasket. :) Good idea about the running in the dark trick. I'll give that a shot this weekend.

devildog1024 have you had any luck? I have the exact same issues on my 1993 5.0 150. I have done it all too, and I keep seeing your name through the forums. I have replaced just about everything with a wire on it under the hood. Timed, vacuum leak checks, you name it over the last 2 months. Have you had any luck?

Well, maybe a little. I was having a problem with my AC after I got it going (the AC). It was switching to defroster when it was on max and I was accelerating. Found a vacuum leak in the recirc door actuator and fixing that improved the hesitation/surge problem a bit. I'm still thinking there's a vacuum issue somewhere but the problem is finding it.

A 1/2-3/4 inch hose, 3-4 feet long, crammed in you ear, use the other end like a stethoscope to find a hiss

OR.... With a blanket and Fire Extinguisher Handy--Do this outside

Crank up, use carb cleaner/ starter fluid---listen for increased RPM at suspected places

The Medic

Already done that. Thanks for the suggestion tough. No fires in the process. :)

Walking or Fixed?

The Medic

Nope, still same issue. Haven't had a chance to manually pull a vacuum on all the lines yet. I'm thinking there might be a leak in the A/C control panel.

CAN YOU JUST CAP OFF IT'S SOURCE, AND SEE WHAT RESULTS HAPPENS?

THE MEDIC

HERE'S SOME MORE AMMO

ONLY THING IN MY CASHE

THE MEDIC

IF YOUR VACUUM LINES ARE HARD PLASTIC AND IN "WIRE LOOMS", MIGHT BE INSIDE THERE....WE FOUND 2 BROKE IN MY DAD'S '86 T-BIRD......I AIN'T NO EMISSIONS MAN, BUT THEY ONLY LEAKED WHEN THE VACUUM SOLENOIDS OPENED THEM TO VACUUM--WE ONLY DISCOVERED IT BY REMOVING THE LOOM

THE MEDIC

That was on my to do list as well. I'm about to deploy for a couple of weeks so I'll do your suggestions then. Thanks for the advice!

BE SAFE

KEEP YOUR HEAD LOW AND WEAPON UP

SEE YOU WHEN YOU GET BACK!

THE MEDIC

Found the issue! It was just an O2 sensor. Boy do I feel stupid! Runs like a champ now.

I have a 1994 ford f-150 5.0,i changed out everything, plugs, wires, Egr valve, vacuum solenoid, vacuum lines were fine, but it came to me, I went and remove the Egr valve, and throttle body, the air holes were stopped up so bad, I had to take a hanger an stick through the holes, alone with some carb.cleaner, kept spraying and scraping, until the hole was completly open, I used a whole of shop towels, it was like pieces of charcoal, but it runs great, no vibrations or nothing, air hole was completely closed off, so you all check that.

Hey, DEBORAH,

Great addition to this thread! Please feel free to help out on the site whenever it can add information that will help people.

Best, Ken

When set the cruise control the speed surges up and down. I have replaced speed sensor in rear end & checked the ring in the rearened. The speedometer has been replaced and no change. I unplugged the controller behind the glovebox and the cruise works fine. However my ford dealer mechanic says it's no guarantee that is the problem. Also I have replaced vaccine lines under the hood. Please help, Thank You.

Bob m

check your throttle linkage and cruise cable for binding, if that isn't doing that it may be your servo going bad.

Thanks for the info. I checked the linkage and it is not binding. I can't figure why it works fine with the abs controller unplugged. Driving me crazy! Thanks for any & all help.
Bob