jacobdsaw

I did my research and found out that i dont have one of the ecu ground outs


IE:


i recently just noticed the 3800 hesitation as well, but i looked for the bolt and took me FOREVER, and figured out it wasnt even there. it looks fresh like it just fell out or something. still silver in the bolt hole.

my question is, is there another way to ground my ECU? because to be honest with you i dont even see wires around that hole to reconnect it. maybe the previous owner did something wrong?

and my last question is could a shop rewire that for me? (rotary specialist of course)

jacobdsaw

So no help?

calpatriot

You could rewire that yourself with some simple tools. Or most any shop can do it. Most likely all you need is a new connector on the end of the wire, but you want to check continuity from that point back to the ECU to make sure there is no open or short in the wiring harness.

You can get a new connector in most any auto or electronics shop. The crimping tool is about $12. Cut the old one off, strip the wire back about 1/4", and crimp on the new connector. Clean up the contacts with a wire brush or wheel. If you really want to do a good job, cover the connector, wire and mounting surface with carbon conductive grease (google it, most shops don't carry it.)

Cinch it down with a clean or new bolt, and you should be good to go.

Note: not all 3800 rpm hesitation problems are solved by improving the grounds.

Flash

iTrader: (2)

+1 for sure. In my old NA, I grounded the ECU at the ECU (under the passenger side carpet). That worked for me on 2 NA cars, but every car is different so it's really going to depend on your situation.

jacobdsaw

i might sound stupid but where is the ecu at for s4's? and what color is the ground wire..

clokker

iTrader: (2)

The ECU is under the carpet in the passenger footwell.

HAILERS

Does you car have the vacuum rack on the left side of the engine? The one with all the solenoids...blue, grey,yellow,orange etc? Or did the previous owner remove those items?

IF the ECU ground wires were not grounded SOMEWHERE, the car would not start.

Is this For Sure a series four car?

calpatriot

Everything you need is in the FSM, available online at the link shown in the FAQ thread near the top of the 2nd gen section.

Certainly clean up the grounds while you have acess to them and the same goes for pulling the injectors and having them cleaned. But do not be terribly disappointed if this does not solve the 3800 rpm hesistation problem. Sometimes better grounding has been reported to solve the problem and sometimes not.

I chased after mine for a very long time, including taking it to two Mazda specialist shops. Then, recently, I got it to go completely away, by doing the following:

1. Check for and clear all codes
2. Check for closed loop operation (see FSM). This test set up allowed me to id that the hesitation corresponded with a momentary lean mixture condition (light goes out during the hesistation)
3. Set idle speed
4. Set idle mixture
5. Checked TPS for dropouts (none found)
6. Set TPS to *exactly* 1k ohms at idle throttle
7. Verified (but did not change) timing and advance

My car now pulls hard right through the 3800-4000 range as if it weren't there.

I can't prove this (yet) but I think the crucial element was the TPS adjustment. Supposedly this helps make sure that the port air and split air are never open at the same time. I think something about that system (it dumps air into the intake when the air pump flow is not going to the port air, split air circuits) was causing it to dump extra (unmetered) air into the intake at 3800 rpm for about a second, and the accurate TPS adjustment solved (?) it.

VAbeachFC

the 3800 rmp problem tends to decrease as the car gets to normal running temperature ... well that seems to be my case

calpatriot

This suggests air fuel ratio. The mixture is supposed to be rich until the car warms up, and then the ECU goes into closed loop and starts adjusting the mixture based on the oxygen sensor readings.

I would bet that if you hook up a voltmeter to the O2 sensor wire, and remote it to the cabin, you will see the O2 sensor voltage go momentarily low (<<0.45v) during the hesitation.

Mine was going low (lean) during the hesistation. It was fixed by adjusting the idle speed, idle mixture, and adjusting the TPS to 1k ohm.

If yours is doing the opposite (going rich during the 3800 rpm crossover), you should see an increase in the O2 sensor voltage at the same point.

Acesanugal

iTrader: (5)

No offense hon, but why are you going anywhere near 3,800 revs before the engine *IS* at NOT?

VAbeachFC

thats a good one, ive always waited to complete warm up tmp before moving the car, deff sucks in the winter time bc it seems like it takes a good 10 mins in winter to just warm up, howerver she loves the cold temps