Low rpm buck, hesitation
 

Hey guys, recently started having a problem with my FD. At low rpms up to about 3500 the car bucks/hesitates really bad, after 3500 the car runs beautiful. I just installed a new throttle position sensor and adjusted it within spec, due to my car hunting for idle after it was warmed up and this low rpm buck/hesitation, since installing it the idle is fine but the buck/hesitation is still there. The engine has 6000 miles on the rebuild. mods are a pfs intercooler and exhaust everything else is stock.

Any ideas to diagnose this would be appreciated.

Clean all ground wire ends and the metal under them .I make ground wires from welding cable .From the battery to the block ,from the block to the subframe .The 1993 models had a hesitation at 3000rpm .Part of the bad stock program .Dirty ground wire conections will make it worse .Be sure the MAP sensor is good with tight fitting hoses .Readjust the throttle position sensor to see if there is a differance .

check the map sensor as garfinkle said what rpm is the car idling at? the ground wires should be easy to fix. just use sandpaper etc to clean all the connections. look on the top of the firewall youll see the cable bolted there and connecting to the top of the motor. usually just corrodes over time and needs a decent clean.

Well, I cleaned up all the grounds and readjusted the tps, just as you guys mentioned. I've driven it about 50 miles and its running great now, no more buck/hesitation at low rpm's, even drove it through are local cruise night. Thanks Garfinkle and Ratjar

zip tie your map hose on while youre digging around in there.

I would also suggest getting a Apexi PowerFC if you still run stock ECU.

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Think about making some custom grounding cables ,do not buy a kit they are easyto make ,I use multi strand welding cable and copper tubing for the ends . A good call for Ratjar and I .

I was looking into buying a Apexi Fc when i first bought it, so i may be buying one of those sooner now. Also, I found a tsb on the ground straps and found mine have the old style straps instead of the later ones which had two eyelets so, Garfinkle i think i'll probably be doing a ground strap upgrade also.

A PFC set correctly will help alot .Check my venders section for the oil pan brace and engine torque brace .If you remove your air pump see my idler replacement .

a pfc isnt something you want to get at a later date. while you may be running just fine now, a pfc greatly improves numerous aspects of the stock vehicle. let alone a modified one.

One more for PFC, best item I ever purchased for the car.

Problem with apexi is that they will not pass emissions tests since they were not made for US spec vehicles. Unless they have changed their programing.

I have pasted the sniff test in Tennessee with the PFC for 10-12 years .I do have to change the program and trick the throttle body to do it because I run 850cc primary injectors .

Where I live in Illinois they don't check for emissions, if i lived more near the city they would, but its good to know if i ever move that I might need to get it tuned to pass emissions.