A/F Increases

[2plus4plus0eq6]

Hey guys,

s14 sr20 here. My A/F is at about 12 at idle. Once I start boosting, it increases to almost 18 sometimes. I have been getting shitloads of backfire lately ever since I accidentally went from 94 octane to 91.

I have a crappy bleeder valve type boost controller installed at the moment. I got a ball and spring type in the mail. Not sure if this could be cause some sort of lean a/f.

Because this is my first turbo'd car, I'm just wondering if what I am witnessing is normal.

Shouldn't A/F typically stay the same whether at idle or under load?

Thanks

[e1_griego]

AFRs should be around stoich at idle/cruise, 14.7:1.

Under load that should be in the 10s or 11s with stock ECU. 18:1 on boost is ripe for failure.

[2plus4plus0eq6]

AFRs should be around stoich at idle/cruise, 14.7:1.

Under load that should be in the 10s or 11s with stock ECU. 18:1 on boost is ripe for failure.

I heard 12 is good for idle since its turbo'd. Anyways.. I seem to be having a problem. What do you think could be causing this?

[e1_griego]

You heard wrong.

[2plus4plus0eq6]

You heard wrong.
Great. Can you answer my question?

[e1_griego]

Leaning out? Could be a dying fuel pump. Or the vac line to the FPR came off meaning it has no boost reference.

[2plus4plus0eq6]

Leaning out? Could be a dying fuel pump. Or the vac line to the FPR came off meaning it has no boost reference.
Fuel pump is a new walbro. Car passed a vacuum leak test. Don't know what else it could be. Point is that there's not enough fuel at wot

[e1_griego]

What size injectors and what turbo? How much boost?

[2plus4plus0eq6]

S14 sr stock injector and Turbo. Running around 10 psi. Sometimes spikes to 14

[Prok0]

I would check a few things..

1. check ECU for fault codes, a lot of times this will point you in the right direction of the cause of the problem.

2. Boost leaks (BOV may be cracking open under load, couplers torn, etc.). Make a quick boost leak tester (can or PVC pipe with a valve in it to pressurize your intercooler piping up to 15-18psi with the car off)

3. check TPS voltage to make sure it is calibrated correctly. If its a bit off or the sensor is bad the cars will run very poorly.

4. check your wideband to insure that the sensor isnt bad (the manufacturer should have a test procedure on this) if the wideband isnt bad check to make sure there are no exhaust leaks inbetween the head and the sensor itself as this will throw off readings..

Cruising/idle you should be 14-15:1 as others have mentioned, under load generally the cars will run low 10s to mid 12s AFR depending upon modifications and tuning.

[2plus4plus0eq6]

I would check a few things..

1. check ECU for fault codes, a lot of times this will point you in the right direction of the cause of the problem.

2. Boost leaks (BOV may be cracking open under load, couplers torn, etc.). Make a quick boost leak tester (can or PVC pipe with a valve in it to pressurize your intercooler piping up to 15-18psi with the car off)

3. check TPS voltage to make sure it is calibrated correctly. If its a bit off or the sensor is bad the cars will run very poorly.

4. check your wideband to insure that the sensor isnt bad (the manufacturer should have a test procedure on this) if the wideband isnt bad check to make sure there are no exhaust leaks inbetween the head and the sensor itself as this will throw off readings..

Cruising/idle you should be 14-15:1 as others have mentioned, under load generally the cars will run low 10s to mid 12s AFR depending upon modifications and tuning.

Thanks for the input.

First of all.. I wish I could get the engine codes. I don't have a consult port since my car is an 89. I know there's an led on the ecu for codes but it's a piece of shit. I'm just waiting until I'm ready to get a piggyback system or something.

My car just passed a boost leak test.

I know my tps was slightly adjusted. It was before on the threshold of the vct so it was constantly clicking. Fixed that now. In order to increase my a/f ratio to 14, do I turn the tps a little clockwise? I'm asking because I think I am burning a little rich. I can smell gas. At idle, my a/f is between 10 and 13.

Could the type of boost controller affect a/f?

[Prok0]

You have to use a multimeter to set the TPS. I do not believe what you are describing is the TPS, it shouldnt make any noise, it sounds like your describing the VTC solenoid. The TPS is located on the side of the throttle body.

The FSM should have a description on how to set the TPS, its the same KA/SR, it should read over 4v at wide open throttle, and at closed throttle it should read between .4 and .5 volts iirc. If it doesnt read the correct voltage at closed throttle you loosen the screws, and adjust it until it does. Once you do that, if it does not reach over 4v at wide open your TPS is most likely bad.

If the LED on your ECU is broken you should still be able to spin the small screw and have the check engine light on the cluster to flash provided whoever did your harness did a decent job.

Can you describe how you boost leak tested the car?

[2plus4plus0eq6]

You have to use a multimeter to set the TPS. I do not believe what you are describing is the TPS, it shouldnt make any noise, it sounds like your describing the VTC solenoid. The TPS is located on the side of the throttle body.

The FSM should have a description on how to set the TPS, its the same KA/SR, it should read over 4v at wide open throttle, and at closed throttle it should read between .4 and .5 volts iirc. If it doesnt read the correct voltage at closed throttle you loosen the screws, and adjust it until it does. Once you do that, if it does not reach over 4v at wide open your TPS is most likely bad.

If the LED on your ECU is broken you should still be able to spin the small screw and have the check engine light on the cluster to flash provided whoever did your harness did a decent job.

Can you describe how you boost leak tested the car?

Ah OK. I didn't know I could adjust the tps like that. Yes.. the solenoid is what I meant. I'll check the manual later for clarification.

I got my harness from wiring specialties. A local shop installed it. Just to be clear. You're saying that by adjusting the screw, the cluster lights will flash? Or can it be done by turning the key on/off in a certain sequence like other vehicles?

The boost leak test was just done at the shop. The Turbo was missing some bolts as long with the downpipe. When I do it at home, I'll take off my air filter and plug the pipe. It has a fitting so I can hook my air compressor to it. I throw a gauge to the intake as well just to check pressure.

[Croustibat]

I'd say FPR line disconnected and poss failed FPR too.
You can't use a voltmeter to tune your TPS. Not without a pricey, calibrated one btw.

Whatever it is, you need to either spend money or sell the car before it is too late. you have the perfect receipe for a destroyed engine soon (MBC, crappy bov with a MAF system, no clue of what you are doing).

First have the problems cured, by paying someone to do so.
Then, if you want it tuned ... pay someone to do so, too, because obviously you cannot.

And stay away from SAFCs. This is the next bad step to take, so i am saying it in advance.

[Prok0]

I got my harness from wiring specialties. A local shop installed it. Just to be clear. You're saying that by adjusting the screw, the cluster lights will flash? Or can it be done by turning the key on/off in a certain sequence like other vehicles?


Yea if you turn the screw over with the key in the on position it should flash the CEL on the dash long flashes and short flashes. Each long flash is 10, each short flash is 1.

So 3 long flashes and 4 short would be Code 34, etc.

Code 55 = no fault codes/all good. If you have anything else I would look in that direction.

[2plus4plus0eq6]

Yea if you turn the screw over with the key in the on position it should flash the CEL on the dash long flashes and short flashes. Each long flash is 10, each short flash is 1.

So 3 long flashes and 4 short would be Code 34, etc.

Code 55 = no fault codes/all good. If you have anything else I would look in that direction.
Alright thanks for the tip. I'll try that when I get a chance. Hopefully it works. I know last time I tried it, the led on the ecu didn't flash. Although I didn't think to check the cluster