Hesitation (Searched... unrelated?) and SHIESTY fuel economy?
 

Hey guys,

I've been trying to resolve the hesitation my FD experiences between 2500-3000 RPM. I've regrounded the connection at the block and added an 8 gauge primary from the negative terminal to the bracket that holds the A/C bottle, both of which are prescribed at fd3s.net. However, I'm still getting hesitation and what I think is piss-poor fuel economy (12mpg?!?). I mean, I'm not driving all that conservatively, but still...

So I'm led to believe it might be a MAP problem? Then again, before I start replacing parts, is this the right direction? What else might I need to check?

Yes, I'm a newb, so flame away if you think that's best. All I want is to get my car running right.

Grounding was never proven to eliminate the 3k rpm hesitation...only the change to a standalone ecu eliminates it in ALL cases.

If you are a complete newb, I would recommend taking your car to a good shop. A search in the West subforum will turn up all the good shops.

If you really want to try working on this yourself, then you need to help us help you. Read the troubleshooting sections in Section F of the factory service manual (FSM). Does anything match what you are having? If so (likely), go through the procedures listed.

What modifications have been made to the car?

The car is totally stock. I'm planning on taking the car to either Mazdatrix or Tri-Point before this summer for some work anyway (got my heart set on a rebuild and street port) but I don't feel like waiting that long to have this issue smoothed out. Trust me, I know who the pros are and when I need to call them, but anything I can do to educate myself about this car beforehand (and after the fact) is worthwhile, IMO.

Thanks for the 94 FSM, BTW. I downloaded it a few weeks ago.. awesome. I guess the reason I'm asking the community is that everything from the air cleaner element to the double throttle solenoid to the injectors to the MAP comes up as a possibility. Just wondering if any of these occurred more or less frequently, or where I should be checking first.

Well, if it is completely stock, it is very likely the pre-cat and main cat are now toasty bits of exhaust restriction. Replacing these items with a downpipe and hi-flow cat (or a new/used stock main cat) will let the engine run cooler, make more power, quicken boost response, and likely increase your fuel economy quite a bit.

The problem with the hesitation is that on many cars, no successful "trick" was ever found out. Only the switch to a standalone ecu fixed the problem. The fuel mileage could be cleared up by the issues I mentioned above, but in addition, it could certainly be things like leaky injectors (which are relatively easy to troubleshoot).

There is little point in running a streetport BTW, unless your car has a full exhaust upgrade and standalone ecu to take advantage of it. Nothing wrong with the stock porting if you are keeping the car stock!

Another point, do NOT take your car to Tri-Point for anything other than them setting your suspension up for competition. They are ridiculously expensive and frankly, from MANY forum stories, don't really know what they are doing. Mazdatrix does good engine work, but they are pretty old school when it comes to modifications and may not steer you right in that department (they do good mechanical work though). I personally think you can find better mechanic choices in Socal (if you were up here in Norcal, I would have a GREAT recommendation for you).

Dang, thanks for the info on Tri-Point and Mazdatrix! A friend of mine went to Mazdatrix for his FC rebuild, and while it was expensive, it seems to have been a good investment. I bought the car in Nor-Cal (Bay Area) so I'd be willing to take her back if it meant that it was what was best for the car.

The pre-cat and cat issue, though, I feel pretty confident I can resolve. I'll start there and get back with results. Thanks for all the help, rynberg!

I'm not dissing Mazdatrix at all except for their modding advice. From all accounts, their engine building and mechanical work is good. There are some good Socal shops so do search in the West forum.

Be aware that when you replace the pre-cat (and main cat, IF necessary), then your boost may raise above 10 psi, which is not good on the stock ecu. At that point, you can install some form of boost control, anything from different sized restrictor pills (invisible and cheap) to a manual or electronic boost controller.