Amur_

Subject line says it all. I've done most of the standard patches for the hesitation, and while it has eased, it hasn't gone away. So I want to ground said boost wire, but the FAQs use an html pic that is wa-a-ay out of alignment. Grrr...
I know that the wire is brown, but what colour/size are the hesh (sp?) marks on it?

ttyl,
Amur_

HAILERS

The brown wire with the black stripe on it. See http://teamfc3s.org/main.shtml FAQ troubleshooting

Six Rotors

iTrader: (17)

Well you don't say what year your car is---if it is 86/87 then look for brown with black stripe if it is an 88 then it is black

13BAce

http://www.teamfc3s.org/faq/FAQ.html#s23800 is easier to use.

HAILERS

He has a 86, at least his profile says that. Ouch! I need to watch what cars I'm dealing with. I did not know about the black wire on later cars and I did not know he had a 86 until Six Rotors mentioned the black wire on newer models, and I then looked at the profile. Thank you for the correction.

Scott 89t2

just a warning. grounding the boost sensor wire on some cars has made it worse. normaly it's the ecu ground that does it.

Amur_

Yep, she's an '86. Forgive my not mentioning that - didn't expect it would matter.

Brown w/ black stripe? Got it. That link took me a page that I had already visited. The html pic is whacked.

I've already done the ECU ground, but the lag remains. And the author notes that he believes that new cats will solve the prob. Great, 'cept that this engine had the lag when she was in my last FC and that car had a straight pipe...

ttyl,
Amur_

nima_taba

AHA! So it's a black wire for the 88's....i knew something was fishy cause I asked the same question last week and I was told to look for a brown wire with a black stripe on it...not finding one, I was just confused.

So basically when you ground the wire you just attach another wire from the point of contact of the black wire to the chassis somewhere...? And this should help out with the hesitation?

BTW - this hesitation, whats is happenign exactly when it hesitates? Some ports opening or something? Exhuast or intake?
Sorry, I'm naive.

Later,
Nima

Scott 89t2

the secondary injectors come on at 3800rpm and the primary ones slow way down. if the secondarys take a split second to long to come on you get a lean spot which causes the hesitation.

added a bottle of fuel injector cleaner can help take it away too.

Amur_

I've been dumping in FI cleaner on a regular basis. No change. Will try the boost ground 2nite. Will post results after.

ttyl,
Amur_

Six Rotors

iTrader: (17)

Nima taba--it is much better to ground to the motor(that's where the ecu is grounded any way).I will be in Calgary about Dec 8/9 if you need any help let me know.

Amur_

Ground to the motor? But the motor itself isn't grounded (aside from existing factory wires, which suck, and any owner add-ons) because the mounts are rubber...

Chassis/frame seems to be the only choice... right?

ttyl,
Amur_

13BAce

It's actually the transmission that is grounded, but since it's bolted to the motor the motor also gets grounded. If you look at the passenger side of the car on the firewall you should see the ground wire.

HAILERS

Nima_tabu....I owe you the apology. I'm the one who said a brown wire with a black stripe. That only true for 86and 87. If I'd looked at the wiring schematic on page 50-25 of the fsm at http://www.iluvmyrx7.com/ I'd have seen that they changed from brown and black to black. I'm still stuckin with my theory about why the factory selected to correct their built in problem by adding an additional ground at the (you have your choice of words) boost/pressure sensor. From my limited knowledge of fuel injection, I find that the pressure/boost sensor is a major player in the fuel injection system. Tells the ECU how much load is on the engine and uses this knowledge along with other factors to enrichen the fuel mixture or lean it out. Hardheaded in texas.

Amur_

Ooh, yeah! 3 hours later and whadda ya get? Completion of the xfer of the power windows from my now-wreckers-bound GXL, new plugs and... oh... yeah. a grounded boost sensor...

And what does that give ya?

S'BYE 3600RPM LAG! We gots the tools, we gots the talent! It would be Miller time if I didn't have to get up at 5am tomorrow.

Got out of the shop, pulled onto 17 and spun her up. Nice and smooth. No lag. At the light, I rev it up smoothly and no lag as she passes through the upper 3000s.
I get my advanced green, and dump it as I pull onto Victoria Street. Ooooh... Not having that brief moment where she stumbles and for a split second you're actually going faster than the damn car ;D is soooo *choice*!
Some ******** in an SUV decided to play 'race cars' just after I got on the road (and passed him - go back to Daycare and park that f***ing embarassment to asphalt, pal!) So, yeah, I was feeling pretty pleased with myself.
3 lights into town I found myself behind an unmarked cruiser and had to back off. If they'd only find a better place for that microwave antenna, it might be harder to spot those guys.

Anyway, had a great drive home! Thank you for your guidance!

And, btw, I grounded the line to the front bolt on the bracket that supports the airbox. Pulled the bracket off first, wire brushed everything 'til I saw steel and then slapped it back together, with a little anti-seize on the bolt. I didn't want my 'new' ground wire to be any longer than it had to be.

And I know the ground wire from the transmission that you're talking about. I replaced the stock wire with 6 gauge automotive wire. "2 a foot?! Christ! I'd like 15 feet, please."

ttyl,
Amur_

Six Rotors

iTrader: (17)

Actually the main negative(ground if you like)wire from the battery is bolted to the engine side of the long bolt for the starter motor or it was when it left the factory.

Amur_

>>Actually the main negative(ground if you like)wire from the battery is bolted to the engine side of the long bolt for the starter motor or it was when it left the factory.

Oh! I once saw a page that recommended running an extra ground from the battery to the starter, but I didn't like the sound of that and so didn't do it. (I've also encountered conflicting opinions about running an extra line from the positive terminal on the battery to the alternator... some say no prob, some say it'll fry.)

And that was supposed to be "$2 a foot?!" at the end of my last post. Why does the best stuff always have to be the most expensive?

ttyl,
Amur_

nima_taba

So guys, just want to make sure of one thing: I ground the black wire to the chassis? Or to the engine? This is the wire running to the fuse box right? What did you do Amur, cause yours seems to be working good! You have a TII though, right?

Hey, Six Rotors, I'll write you and maybe we could hook up and see if we can't fix this problem. What are you coming to Calgary for? I don't know if I'll be able to cause I'm having knee surger this week and will be on crutches for a while, which will make leaning over engine of my rx7 kinda hard....

Thanks for all your help guys!

Nima

Amur_

I have a 1986 GXL (she's a GXL with all the choice goodies from a GXL xferred over into her). Non-turbo. The only other thing of significance is a K&N performance filter. No CAI. Yet.

I had completed all the other mods that I had found to cure the 3600 rom stumble...

- added an extra ground wire to ECU in the passenger footwell.
- added ground wires throughout the engine compartment.
- semi-regular treatments of fuel injector cleaner.
- had computer circuit boards (and *all* other circuit boards) re-soldered. But that was mostly an upkeep issue for me, and wasn't directed solely at the stumble.

I grounded the boost sensor wire to the chasis. Make sure that the wire, and the bolt that your attach it to, is contacting steel and not paint. Use a wire brush or sandpaper or scrape ther hell out of it with a screwdriver. Whatever it takes.

Saw a page a while ago (about FDs) where the author stated that the lag was a question of amperage, not voltage. Whatever. I finally got rid of the damn stumble.

Here's what he wrote (my apologees to the author for not getting his permission first...)
_____________________________________
3k Hesitation Fixes
Here's the 3000 RPM hesitation fix that I did on a couple of Chicagoland area RX7's:
1. Put thick extra ground strap from extension manifold to firewall (use multi-strand stereo cable, and clean metal using strong wire brush)
2. Clean the ground lug at the bottom of the motor and move it to an opening on the engine block
3. Replace stock cat back ground with multi strand stereo cable
4. Affix a new ground point from down pipe/precat to frame (use multi-strand stereo cable, and clean metal using strong wire brush) the key here is to put the ground strap on the down pipe's flange, not the main cat's flange
5. Replace battery (if needed)
6. Clean fusible links. Right next to your battery's positive cable there's a little fusible link box there (you should see a "Main 120" on it, that's the box I'm talking about) you need to take off the cover and you should see the positive and negative in and outs clean the contacts thoroughly with a wire brush. This is a very important step
7. MOST IMPORTANT STEP!! Make sure your Alternator belt is tensioned to stock specs. This is the main cause of the 3k hesitation. I would suggest buying a new belt and make sure it's tightened using a belt tension meter (over tightening can cause water pump failure
8. Reset your ECU by disconnecting it and pressing the brake for 5 seconds
This should work, I did this on several 93-94 RX7's. People out there think the 3k hesitation is a voltage problem but its an AMPERAGE problem. the ECU needs to see a consistent amount of AMPS especially during the point the secondaries come on. The manufacturers of the 93-95 RX7s alternators (Mitsubishi?) used cheap parts and I come to believe that the 2nd gen alternators, although they are basically the same alternator were manufactured better back then.
__________________


ttyl,
Amur_

rxspeed87

yeah yeah I know this thread is OLD

but just wanted to add about the wire from the alt to the batt

I ended up doing that with no problems and it has been on there for about 3 years now
so don't think you have anything to worry about doing that

RETed

Add this one also...

FC's made after Nov 1986 with VIN's after ...0522332 should not have this problem. Kudo's go to Dale Clark for this TSB tidbit a few years ago - I just dug this up from my crap.


-Ted

rxspeed87

wait ted are just to make sure you saying that anything of the 87.5 later cars do not suffer from the problem?


what was the cause of the problem do you know?


reason I ask is I just took a look at my car and the pressure sensor is a n327 while the ECU is a n326
least by readind the label


but still have the problem with 3800rpms lag

still think grounding might work even though it says I have the 87.5+ sensor?

RETed

Dale Clark posted that piece of info YEARS ago on the TeamFC3S list. I'm just regurgitating it, since I found it laying in my crap a few weeks ago.

This is off an official Mazda TSB, so Mazda was aware of the problem and it looks like they fixed it during production (rewire?). This would explain why some people get no effects from doing this additional grounding.

ALL FC's should go with additional grounding - not just the boost sensor. On almost every FC I've worked on that we added more grounds, the engine just plain runs better. This has to do with the ECU grounding on TOP of the engine, and grounding the engine better helps with this, ignition spark. and alternator voltage.


-Ted

rxspeed87

yeah I did notice a difference when I went through and regrounded the batt at a few different spots

as well as direct wire the alt to the batt

still have a few more grounds I need to do though
like the ECU and boost sensor

silverrotor

iTrader: (1)

Rich, you need to rid yourself of the crunch ol' harness and get a standalone EMS with fresh wires. Than you won't have to ground everything In site.