After finally getting my 87 TII running in June, I've noticed a few things not quite right. I know I may have a vacume leak from the intake gasket since one of the studs broke off on me and one bolt stripped, but I'm going to fix those next week.

1. Idle, when hot sometimes will restart then immediately die,
also floats from abot 550 - 800 occasionally but usually runs
well.
2. Hesitates past 6000 rpm. Car has some sort of cheap feul cut
defender in the line to the boost sensor. But only does this
during the first 15 minutes of driving. Honestly haven't tried
warming it up that long first.
3. Backfires when I come off the gas after driving hard.
(probably running rich? no black smoke at idle though)

I have a full RB exaust and an HKS supermeagflow intake.
The car is otherwise completely stock. Could these be mostly related to a vacume leak? Throw me any ideas, stuff to try whatever.

Thanks

 

Sounds like a vacuum leak to me. It will definitely cause idle problems. It also fits with backfiring. The reason is that the anti-afterburn valve needs a high vacuum to actuate. You can't get that with a vacuum leak. Also, if the vacuum leak is big enough, it could be playing some havoc with boost, causing A/F ratio errors. Above 3800 rpm and WOT these values are fixed in the ECU. As the engine gets warmer, an error might not have as bad an effect. Do you have an A/F ratio guage? I hope that while you are having this problem you are not running lean. We all know what can happen to a Rotary when it's lean. Good luck!

Irv, Keith's dad

 

Thanks Irv
That' kind of what I figured, hadn't thought about the anti afterburn valve though. I don't think its lean, I had the AFM adjusted at a shop up here and I get about 325 km on 45 L of gas, which I figured was also the leak.

 

If the car doesn't have an upgrade fuel pump, you're in danger of blowing the engine up.

The high RPM hesitation is usually due to an ignition misfire or bad TPS.&nbsp If it's ignition, change the spark plugs and spark plugs wires.




-Ted

 

How 'bout the timing? Too far advanced?

 

I changed the plugs and wires in June and the timing is set to stock specs.
Thanks

 

Andy,

I am concerned by your reply to my post. You see, I stated that above 3800 rpm under boost, the AFM makes no difference! The ECU computes fuel based on rpm and boost! If the actual air being sucked in by the engine doesn't match that predefined curve, you are going to have a mixture error. If it is a lean error, you got trouble! Please, please, do not drive the car hard until you get this corrected - it could be a $2000 + error.

On another note, you mentioned that your AFM was "adjusted". I just rebuilt one. I couldn't find any adjustment. Does anyone know about this "adjustment"? Is there a procedure someplace for it? It isn't in the factory service manual. Thanks all.

Irv, Keith's dad

 

Irv

Under the plastic cover where the plug is there's a half cresent gear kinda thing. My understanding is that by advancing it along the teeth on this thing you can adjust the air/fuel mixture, yes I know the other way too, as described in the manual.
Am I wrong, I guess so since you rebuilt one and seem to know your stuff from other posts I've seen you reply to. Anyway, I think its safe to say fuel management is not really my thing.
I am well aware of the money it could cost me, since I just put this engine in and really don't want to do it again. My TPS is good
the AFM passed all the voltmeter tests as per the manual before the "adjustment" (I think I'll retest it in the morning). Do I really need a bigger fuel pump with the limited mods I have as RETed says. I checked the pressures before and after the rails and they were good according to stock specs.
I can't afford another engine, so any help would be greatly appreciated.

Andy

 

I wouldn't call a racing beat exhaust and air filter limited mods. I'd call them a disaster. do you have any idea what boost you are running? I bet it's over 10psi. my friends "perfect" running engine lasted about 2 weeks with those 2 mods.

I'd check the TPS for the hot start up idle problem. that fixed mine.

did you check the fuel pressure at idle? try checking it at 7000rpm... when you are using fuel.

and your gas mileage is way to good... well umm bad.

before I got my ign box, to get 325km I needed 55Ls of 94.
ign box gave me about 50km a tank more.

 

if it doesn't use the AFM after 3800. then how does the S-afc work...? I'm pretty sure it still uses the readings.

 

So I AM going to have to sink more money into this thing!
!$##$$#%$$%$$$$@@%^
Am I going to kill my engine with boost spike? running lean? detonation?
What kind of shopping list am I looking at?

 

Hey Andy. No, you are not wrong. Now that you mention it, I have seen posts where people have messed with this "adjustment". I have never needed to change it from stock (running Bonez Intake, hi-flow cat and HKS 60MM or 70MM, not sure which, cat back). Of course, as Scott has so kindly pointed out, we are talking about an S-AFC here, so I am bowing out, I know nothing, nothing ....

Irv, Keith's dad

 

Hey Keith,
I would have to agree with most of these posts above... We don't want to make you scared, we just don't want to see your beloved rotary blow up....

As far as the shopping list you will need goes:

- Boost and Air Fuel Gauges (a MUST have for anyone with a Turbo Rx-7. Even without modifications, it's a good Idea to have these tools)

If you do find you are running lean :

Bigger Fuel pump and Bigger injectors is what you'll need.

As Scott said before, the "limited mods" you have done are not "limited". Those are the Biggest mods you can put on your car before you start buying bigger turbos and FMICs and stuff like that. Just think about how much HP you get from the exhaust alone...
I might be a good idea to check out that "cheap" FCD. Maybe spend a bit of money on a Racing Beat one.

Good luck with everything,
Mike

 

Oops, i just realized I put Keith instead of Andy, Sorry about that guys...

-Mike