Hey guys.

Here's the thing:
I've just started my freshly rebuild engine (street port). Started @ 1st try, lots of smoke has usual and more or less crappy idle.
Looked to the wide-band and it reads 11.2 AFR.
Got the idle down @ 1k-1.1k rpm easly with just a touch of the idle screw. Still same AFR ofc.

I left him idle for about half an hour, nearly all smoke gone and i just tap the pedal to rev him some.... and be barely revs.. if I'm gentle, i can get the revs up to about 2.2k rpm and it "stalls" out, getting picked up @ idle and doesn't die.
If I press the pedal a little harder, it doesn't even go up to 2k and just dies out.
I've managed to blip the throttle "in a right" way and get him to nearly 3k, but it always "stalls" out and sometimes (just sometimes) dies.

I do think I might have way too much fuel and need to lean out a lot, but I'd like to know if there's anything else I could be missing.

Engine was rebuilt by rx7store but installed by me and a friend (1st rotary for both of us). I would gladly take the car to a rotary tuner specialist... but there aint none in my country..


Mods: Streetport engine, 850/1600inj, Full exhaust, IC, PFC, intake, HKS twin power, ACT flywheel, non-sequencial twins.
Base map is a BDCmotorsports map.

Any other possibilities besides being way to rich?
What should my fuel pressure be @ idle?

Thanks

 

As measured with the vacuum line disconnected, most people run 40psi. First check your TPS.

If that's ok, watch the wideband when you tap the throttle. Does it go super rich? Or does it go super lean? There may be a tip-in problem or a problem with a fuel map. The best way to troubleshoot that is to log "Advance" (ONLY advance, do not log anything else except Auxiliary). Then make a chart of Advance InjFrPr (primary injector pulsewidth), rpm, TPS voltage, and auxiliary (wideband). This is some advanced datalogging techniques here.

During tip-in, TPS voltage increases (curve rises, usually in a smooth manner). Injector pulsewidth SPIKES. The tip-in settings determine how high the curve spikes (enrichment) and when the curve spikes (sensitivity).

So if the throttle is not moving (curve is flat at a given point) and the car runs lean/rich, you need to start by adjusting the fuel map. It is NOT a tip-in issue if the throttle is not moving.

If the throttle is opening (curve is rising), the car runs lean, and injector pulsewidth is barely moving or moving slowly, the car needs better tip-in timing--the fuel needs to kick in earlier. There are a couple tables that determine the tip-in settings. Accel vs TPS 1 is a big determinent of this, and INJ vs TPS 1 can help as well. These tables can also be modified if there is too much fuel applied on tip-in, but that is rarely the case on a car with a base type of map.

If the throttle is opening (curve is rising), the car runs lean, and injector pulsewidth is spiking, the car may simply need more tip-in. There are a couple tables that determine that. Accelerate Injector works sometimes, although it can overcompensate easily. Sometimes more Accel vs TPS 1 is needed. These same principles can apply for a correction a situation where too much tip-in fuel is being dumped in.


If you're interested I can post up some logs later which demonstrates the process of diagnosing a tip-in problem. But first do the normal checks like fuel presssure, vacuum leaks, and sensors.

 

All sensors seem to be working correctly, but I'll double check. I found 1 vacuum leak, but that only helped the idle a little. Since I'm non-seq, i barely have any hoses so I'll be just checking the caps.
The fuel pressure I've set was 35psi with the vacuum line connected. Wasn't 100% sure on the way ppl set it. Guess I figured it wrong.

When i gradually (very very very slowly) accelerate, the wide band shows the AFR falling to 10'ish, then it "stalls" back to idle. If I'm do a normal throttle blip, the wideband doesn't update fast enough for me to see it before its already showing 16AFR (stalling).

I'll try that data-logging. Thanks. That way I can see if I'm going rich, lean or something else is fubar.

Any chance a badly adjusted throttle cable can also "not help" this?

 

This sounds like you either have the wrong map sensor selected or the line not correctly installed.

What is the vacuum reading on the PFC when the key is in the on position, but not running? it should be around 0, but can be as much as -50 or so

What is the vacuum reading on the PFC when the car is running? If it is not changing then you have the line either disconnected or hooked to the wrong location.

What are your VTA1 and VTA2 readings on the PFC? This will tell us if the TPS is installed correctly

 

Ok. Dunno how i missed this:

VTA1, VTA2 and PUMP read nearly 5v with only the key turned on.
After I disconnect the TPS, there are no changes on the Voltage reading... something is defenatly wrong. Going to hit the search. Guess you were on the mark there BR.
Any ideas?


PS: vacuum reads -25 with key turned on, -350 @ idle (1k rpm)

 

The TPS must have been removed at some point. It is spring loaded, which means that it was most likely not install it correctly. Remove it and reinstall, check the commander for readings. If you can't get any reading then the TPS is faulty or the signal wire is damaged.

PUMP? I think you are referring to Fuel which is the Fuel temp sensor that you would have removed for the 1600cc secondaries.

Sounds like you have the correct Map sensor selected.

 

Ops, yeah. FUEL
though it was the fuel pump volt.

I didnt remove the tps, but im not sure about the mechanic that removed the engine (no longer around). Going to remove it and give it a try. Will post back in a few.

Thanks.

 

TPS is cracked. Need to source another one.
Thanks for the help
I don't preview any more problems after the TPS, but will post how it goes.

PS: Is the TPS equal to any other mazda or car? Like the miata or something?

- Carlos

 

carlos, how fast are u planning to run on this set up? 850cc is a bit too much for primary... and u will waste some gas when u do street driving.

 

How fast? As much as I'm able.
Its not DD and will see trackdays.
Planing on going with BNRs later and AI.

 

hope you get it working right.