Hesitation when boosting

underscore

Well-known member
The car has been sitting since October or so, I fired it up for the first time tonight and it drives beautifully under vacuum but as soon as it hits 0psi or goes into boost it starts hesitating and feeling like the fuel is cutting in and out very very quickly. Drop back into vacuum and it's fine again. No CEL but I'll check for codes tomorrow and poke around things a bit but in the meantime if anyone has any suggestions on where to start looking they'd be appreciated.
 

underscore

Well-known member
It has a code 35 Open or Short in Pressure Sensor. Which is odd because I had it unplugged previously with no error code, then I plugged it back in yesterday. I'll try unplugging it again and if that doesn't change anything I'll try my spare ECU.
 

underscore

Well-known member
I unplugged the pressure sensor and no real change. Idle was a bit high at 1100 and it would miss a bit but catch itself. Swapping to the other ECU and idle dropped to 900 but still missing sometimes. Then as I got home it started sounding like a Subaru and I think it's only running on 3 cylinders.
 

underscore

Well-known member
I confirmed it's only running on 3 cylinders, I pulled the wires off the cap and there was no change when I pulled off #3 (I think it's #3, the 3rd from the timing belt/2nd from the trans). I noticed it arcing between the cap and wire when I pulled it off so I'm thinking either the injector isn't firing, injector is plugged, or the spark plug has shorted but I'm open to more ideas. Swapping the ECU made no difference.
 

grip-addict

Active member
What gen motor/ECU are you using ?
Try starting with refreshing your spark plugs. I put denso plugs in one of my German cars and it immediately misfired under boost. Drove just fine in vacuum though.
 

underscore

Well-known member
gen 2 RC motor and ECU. It looks like you're right about the plugs, #3 looked to have good compression, the injector wiring looked okay and the plug smelled a bit like gas. I swapped it with the #4 plug and left #4 unhooked and it still sounded like it was still running on 3 cylinders, not 2. #2 and #3 had a good amount of oil on the top of the plugs but the tubes looked clean which is weird. The shop put in Denso IK20 iridium plugs and the manual calls for ND PK20R8 or NGK BKR6EP8 which are platinum, so I'm going to try switching back to one of those. It might be a fluke but I've seen more harm than good come from running anything but the OEM recommended plugs on a stock ignition system.
 

grip-addict

Active member
eyyyy if it's just plugs then this is probably the most successful forum thread in the new alltrac.net era :D

everyone has their own taste in spark plugs, but as long as it works, who am I to judge :)
I personally do NGK BKR7e's which are only supposed to be good for 5k miles, but I just change them every spring along with the yearly oil change.
I had IK20 or IK22's on my camry a long time ago (can't remember exactly which) and didn't notice a difference in mileage or power, so I just went back to factory dbl platinums there. Also, the downside to iridum is that you can't gap them :\

Notice anything weird on #3's plug?
 

underscore

Well-known member
Changing the plugs got it running on all 4 cylinders again which is excellent. #3 looks the same as the rest to me but I'll snap a pic and see what you guys think.

Now it's throwing an intermittent CEL with codes 22 and 54 so I'll have to dig into those. I'm guessing I knocked something loose while moving the IC around to get to the plugs but we'll see.
 

Gert

Active member
22 = open or short in water temp sensor.
54 = intercooler error.

Plugs: I have the platinum ones. They last about 80.000 kms. I hate the hassle with the intercooler etc.
 

underscore

Well-known member
A bit more test driving and it seems to be solidly running on all 4 cylinders, and the codes only seem to be showing up after it's been driven for a while and things are thoroughly warmed up. A bit annoying to try and troubleshoot since I don't think doing the BGB tests cold will yield anything useful. I might just start by swapping the ECU again since that's easy lol.
 
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