Wont boost over 10psi

[o 16K o]

Ok I've had my turbo setup for around a year now all was running well... Well about a month ago my car started having a problem. The cars runs really good out of boost and even in boost up to 10 psi.. I have the wastegate set to 18psi.. Engine boosts hard in 1st and 2nd but then 3rd, 4th, and 5th hit a brick wall after 10psi... It like backfires really bad and loses power...

I'm sure 1st and 2nd run good cause it doesn't boost higher than 10psi (holset hx35).. I thought maybe it was spark blow out so I got new plugs and gapped them .25 to be sure.. Runs better now but still has the issue. No CEL.. I did get a new auto zone distributor recently.. I've already exchanged it twice cause I'm thinking it might be the cheap distributor??

I'm stumped I don't wanna start pouring money into it if its something simple..

 

[XpL0d3r]

Could the head be lifting under boost? I suppose you could check the wastegate spring too. I'm wondering if it's opening early for whatever reason and confusing the hell out of the ECU.

 

[o 16K o]

Possibly but doubtful. ARP headstuds and hks bead head gasket.

Might be overboosting... Its on a stock map sensor but I tuned it to run rich in the last column.

 

[TokyoSkies]

It almost sounds like a fuel delivery/map issue to me. It's falling flat under load, so I would be looking at your fuel pump, injectors, and ECU mapping first and foremost. Ensure your WG spring isn't getting stuck somewhere under load or something.

 

[o 16K o]

Its just weird it would run fine for almost 2 years and now I'm having this problem.. Seems like it might be a timing issue with the way it backfires..

 

[xxBLOOD88SHOTxx]

You do have a 3bar map sensor correct?

Have you checked the gauge and made sure it is accurate?

What size wastegate/type

 

[o 16K o]

Stock map sensor but I tuned it rich in the last column..

Haven't check boost gauge but seems to be accurate..

Its a godspeed 38mm wastegate

 

[xxBLOOD88SHOTxx]

Stock map sensor but I tuned it rich in the last column..

Haven't check boost gauge but seems to be accurate..

Its a godspeed 38mm wastegate

Well, any one of these could easily be the culprit.

Do you have boost cut set or a a/f mixture safety cut?

I would get a 3bar and test that gauge asap.

 

[got traction]

Sounds like it is hitting boost cut. First thing I would change would be the map sensor. Upgrade to a 3bar, then go from there.

 

[TokyoSkies]

Sounds like it is hitting boost cut. First thing I would change would be the map sensor. Upgrade to a 3bar, then go from there.

Yep. Map sensor needs to be replaced for sure, which I would then re-tune for (that way you don't have to compensate by running rich). Next, may want to look into a more reliable Wasetgate. The Godspeeds aren't horrible, but drop some cash on a Turbonetics or TiAL. It's well worth the investment.

 

[Radyjr]

Stock Honda Map Sensors if am not mistaken only good for some where around 11.2 pis. (also depends on altitude)

 

[Failsafe88]

Map sensor is causing your problems along with the fact that you have an eBay turbo set up.

 

[James315]

What size injectors? I would be willing to say its a combination of running out of fuel and the map sensor.