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Surging at 35-40mph?

2K views 2 replies 3 participants last post by  therocknss 
#1 ·
Like the title says, my car is surging between 35-40mph ONLY, and I have no idea why. I did a few things before this started happening and I don't know which could have caused it (if any).

Basically, I redid all but the head gaskets, cleaned out the throttle body, ran some Seafoam spray through the brake booster line (it's back in tight), replaced the PCV valve, replaced all the spark plugs, cleaned the injectors, and replaced the fuel level sending unit.

What I'm thinking it is is that when I was installing the new fuel level sending unit maybe I got some crap into the gas tank and it's clogging up the fuel filter? But it only happens between 35-40mph and around 1300-1400rpm for a few seconds and not at any other speed... It's the strangest thing and I've read about it happening to a few other people through Google and they ended up spending $2k in some cases and didn't get it fixed... Then stopped updating their thread so I don't know if they ever did find out what it was.

Has this happened to anyone else? Anyone have any guesses as to what this might be (please guess something cheap because I'm broke lol)
 
#2 · (Edited)
It is probably not a plugged or restricted fuel filter the way you describe. A quick test for everyone paying attention is get on it pedal to metal and see/feel the response. A restricted/plugged fuel filter will act like a weak fuel pump. When you first get into it, it will respond m normally. Then as you stay on the throttle, it will start to loose power/slow down. The longer you stay on the throttle, the worse the condition will get. Now one should be aware that this reaction can also be felt from a plugged exhaust in which case you simply drop the down pipe flange and retest. NOW, the correct way to test the fuel pump and or filter would be to put a guage on the test port and see if the pressure and volumn of flow is correct.

What you are describing sounds like a vacuum leak or a MAF sensor issue. I would do a diagnostic scan and check all the "live data" info to see what is out of normal.

By the way, some of those cases you mentioned where they just disappeared or ran out of money happened from lack of knowledge or failure to have a good diagnostic preformed by someone with the "know how" to do this correctly.

Hope this helps so you too do not go down the road of throughing $$ at the propblem. Good luck, Jake L.


PS, U TUBE info or whatever other sites on line that have 'fixes' posted can be VERY MISLEADING causing even more unnecessary spending.........
 
#3 ·
surging

I have been having the surging issue for about 1 year. It is getting lots worse. Intense racing scanned the car and everything engine related seems ok (as far a the surge goes). I have came to the conclusion it is the trany applying and unapplying the lockup converter. I spoke to my trany guy and he said he sees this issue often. He told me about several things internally that is letting the fluid get by to try and lock converter (mainly worn parts). I took my spare trany to him to fresh'n up. When I get it back, I will swap it out and hopefully solve issue.
 
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