Engine surging when engines is warmed up

Tiny
1GARYZ
  • MEMBER
  • 1993 FORD FIESTA
  • 1.3L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 175,000 MILES
Car starts great and runs revs up fine until engine warms up then opening throttle engine will not accelerate just run cut out run cut out at a precise beat, open throttle larger the cycle becomes faster of trying to accelerate and cutting out. Disconnected the temperature sender/sensor engine will run normally cols and accelerate when hot but after warm fast idle and varies, played with the throttle body air screw to correct problem helped some but not like before in smoothness. Also disconnected electrical idle control air bypass plug and had to increase the idle air screw. Engine warmed up and ran inconsistently. Reconnected idle control bypass and drove car, not the same power or response. Once warm sitting in traffic engine heated up rapidly, at speed engine stayed at normal temperature. I know there are two engine settings one for cold one for at temperate has the pcm taken a partial dump but will run in the cold program? Reconnecting the temp sensor engine at temp will not accelerate and just runs cuts out runs cuts out at anything much over idle. Out of ideas need help. With everything connected no engine light comes on during problems cold or at temp. With temp sensor disconnected or idle air control bypass disconnected engine light comes on and stays lit several seconds after start up.
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Tuesday, January 7th, 2014 AT 4:14 PM

3 Replies

Tiny
HMAC300
  • EXPERT
When you unplug a sensor it richens themixture of fuel and goes to open loop. So check for a vacuum leak a can of choke cleaner sprayed at different areas around intake/ throttle body will show a vacuum leak as well as hoses off. If you dont' find anything, check intake duct for being on correctly wit no holes between MAF and throttle body. Then if stilldoing it rap maf with a screwdriver handle see if it changes. Also check O2 sensor for a burnt wire hitting the exaust and burnt through or grounding out.
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Tuesday, January 7th, 2014 AT 4:37 PM
Tiny
1GARYZ
  • MEMBER
Have done that already, thanks for the info on the system going into closed loop. No leaks at manifold cracked hoses leaking hose or intake to air cleaner cracked or leaking. I had the MAF off of the filter try and observing the flow plate moving and gently augmented it during the studders, hard to do but it seemed to help but it was so hard to manipulate it I could not do it real well to be sure it was the issue or not. Popped it with a screw driver thinking it was stuck as well. All this happened when I took the valve cover off to replace a leaking gasket. I had to take the throttle body off as well to get the cover off did it years before no problem. Pulled the throttle body off a second time just now and the gasket made a perfect seal as evident by the crush patch on the gasket when you use gaskacinch on gasket they come off in one piece to tel l the tale. There are 2 tubes one to the heater water pipe the other to the IAC BPA that were pretty clogged up so I just made a loop pipe from the heater port to the IAC BPA which them goes back into the block. I played around with it and got varying results the best being blocking the line from the heater y pipe and letting the other pipe to the ICA BPA be blocked the other sied goes directly into the block and senses the water temp from there rather than the flow the way it senses with the "u" pipe setup it obviously gets too hot that way from what I am seeking. I think possibly the line going to the throttle body dropped some of the heat there then on to the ICA BPA. I will hook it back up this time the original way and see what happens before the lines were pretty clogged up so it got little flow and just senses the temp from the water more or less stagnant in to line coming to it from the block. I do not know what I did this time any different than before to have gotten this issue. One other side not I just got the car smogged and the one lead line you are suppose to ground out to check the timing is set correctly, when you ground it out the engine shuts off immediately like you shut off the ignition switch so that is why I have been fostering the idea the ecm may have an issue. I should have just let it leak put down some cat sand on the drive and rinsed the engine off one a week and avoided all this.
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Tuesday, January 7th, 2014 AT 5:04 PM
Tiny
HMAC300
  • EXPERT
The maf has no moving parts so what you did you must be talking about the throttle body. Normally a car won't run with the maf off or out of the duct work and not connected to the throttle body. It this happens when the tbi was pulled off then check for improper installation like the plate hanging up or a broken gasket also clean the throttle plate on both sides with choke cleaner as well as iac hole. If the ecm is under the hood it is possible that it has water in it. But not having that car in U.S. We don't have any info so i'm giving you general answers. You might try scanning for codes and check fuel pressure wit h a gauge as it may be low causing that or maybe a fuel pressure regulator problem.
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Wednesday, January 8th, 2014 AT 6:39 AM

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