Need some experienced guru on this. My car have been suffering lean spot at 3400-3600 rpm only during partial throttle at boost, Full throttle run is fine. It will move from mid to high 14s even at boost around that area. I'm tuning with uprev tuner. No matter how much fuel I add it still goes back to the same AFR. I was using the same fuel setup from my previous HKS SC which worked fine for me. It is 6 x 550cc injectors, walbro pump using standard fuel pump assembly with no return (Not using the regulator which came with the TT kit). I had a bad MAF socket previously which i had replaced. However outcome is still the same. I'm thinking if it would be beneficial to replace the standard maf housing to a 3" size as it would be the same diameter with my intercooler to TB pipe.

Current setup listed below:
PE TT kit
550cc injectors
walbro pump (returnless with stock in-assembly regulator)
JWT S1 cams
Okada coils
Built 8.5:1 engine

Let me know if there are any other details needed. Thanks.

 

Try logging MAF voltage in the lean spot and increase the MAF multiplier around that area. It's more of a 'blunt' way to tune but sometimes it's needed. You'll also make sure you're MAF is working properly.

 

^that would help, also check you tip in enrichment

 

why not send your logs over to uprev and have them etune it for u.

 

I would do this. They won't etune boosted cars but they can sure tell you if there is a problem with maf signal or you just need to make adjustments.

I also would add fuel in the maf map instead of on the fuel map. That way you can see at what voltage it's lean and then go straight to that maf voltage in the maf map and increase it. Try drastic changes to see if adding fuel even helps.

Also, does the car fall on it's face? going to 14a/f in boost would make the car stumble pretty bad so if it's not stumbling you might need to look at an exhaust leak before the o2 sensor causing a false reading.

I wouldn't recommend using a larger maf housing. As noted by a few people that have tried it you have to adjust the whole maf multiplier in osiris and it's a huge pain to tune it out correctly. Most competent tuners do'nt want to do it so it doesn't sound like a smart thing for an end user to try. The maf is definitely not limiting your power at this stage.

 

Since you say its at part throttle, perhaps the ECU is having trouble getting out of closed loop? Which can explain why no matter how much fuel you add, the ECU is still leaning it out to ~14.7.

 

Thanks. I will give it a try tonight. Appreciate the help. Keep you guys posted.

 

 

How should I go about this? Should I set the close loop AFR richer or is it something which I've setup wrongly. Please advise.

 

Ok. I'm now looking at my MAF voltage and values are set alot lower compared to stock ROM. Is there a relation on what voltage and value set which determines close loop/ open loop?

 

Also check your fuel target table. Set all columns except the first column to 11.5. This will aid in troubleshooting if the ECU is targetting 14.7 in boost.

By the way (to the other poster), there isn't a tip-in enrichment in uprev.

 

Just tried. Didn't work. I'm now looking at the logs. How do I increase the MAF multiplier? By incresing the value at the certain voltage?

 

Exactly... do it for the one above/below the target value as well just to be sure. If you multiply the existing value by 1.25, that's the same as adding 25% fuel on the fuel table in those areas. Likewise, multiplying by 0.75 would be like taking out 25% fuel.

 

but he said partial throttle and in boost so that means he's probably above 20% tps which means it will be open loop. The car can still make boost at 50% tps and since it's over 20% it will be in open loop.

 

Well thats the problem, maybe the ECU is not going into open loop for some reason (Perhaps TPS reading can be off). I have had that problem in my car, even with good tps specs. Cant explain why though, all I know is that when I force it to open loop, it does not lean out during the same part throttle conditions. Perhaps the OP can do a quick test like that, force the ecu to be open loop and go for a drive. In mine i just disconnect the o2's so the ecu automatically goes into open.

 

the problem is only at 3400-3600 rpms though. So why would it go from open to close to open? He shouldn't be anywhere near 20% tps if he's under boost. It takes more than that to boost.

 

In that case, I would take out the MAF and clean the sensor. With CRC MAF cleaner, dosnt hurt to see if thats causing it. I always had issues with the MAF going out of wack randomly, then everytime I cleaned it, it went away. So i just deleted it.

 

Saw some changes after increasing the value of the MAF voltage. Now it only lean out during 3200rpm at lower throttle position. I too thought it was the MAF sensor hence taking it out so many times and damaged the plug. I'll do more test on wednesday. Hopefully this will solve my issue.

Another thing I didn't quite understand is the cranking enrichment. Everytime I start up cold, it will fire up and die off immediately. No signs of flooding the cylinder though. Any insights?

 

You're leaning out very badly on your cold starts...

it runs open loop for about 30 sec on cold startup so my guess is your MAF is jacked up or the MAF table itself is totally off. Try setting MAF table back to stock (or HPX if thats what your running) then starting over.

I basically did 80% of my tune on MAF adjustmanets alone starting with cold starts, then idle, then no load revving, then light load, then boost... the fuel comp table is +/- 5% top to bottom.

 

yep, with osiris i used my maf table for almost all of my tuning.

Since you said the maf table values were below what they were stock and now you're boosted i would say your maf table has been screwed with and messed up.