Major Hesitation

RiceBox · Nov 22nd, 2002, 11:35 AM

When my engine is cold it will barely rev above 3700RPM, it is also shudders badly when I go past half throttle. Even when the engine is completely warm it will still sometimes hesitate when I go to wide throttle openings. I've changed the cap, rotor and plugs, wires, and put STP fuel injector cleaner through the system. Didn't really make much of a difference. Any other ideas?? MAF, TPS, O2 sensor??

LittlebittaContact · Nov 22nd, 2002, 08:22 PM

im thinking if any of these were bad, your ecu would throw a code, HOWEVER, you may have to adjust your throttle position sensor. ive found a hole in my fuel this way (you know, how you hit the accelerator real hard and it hesitates a second before it revs) but when i did this i also adjusted the timing a bit. thats my .02

RiceBox · Nov 23rd, 2002, 07:41 PM

Actually I after doing some research I found out that the E16i doesn't have a TPS, so I'm now guessing it's the MAF. I'm, going to test it when I get a chance.

LittlebittaContact · Nov 23rd, 2002, 09:13 PM

Yes, it does.

as a matter of fact, you have to remove it to get the MAF off...

thier are 2 screws holding it in, and its adjustable.

RiceBox · Nov 23rd, 2002, 09:52 PM

Wierd. My Haynes manual says that only the GA16DE has a TPS

Anyways, it is only bad when the engine is cold, so what could that signal???

Crazy-Mart · Nov 24th, 2002, 01:36 PM

this tps doenst run like hundas... neither subarus.... its coupled with the Air flow sensor (wich is no MAF) to get the right mixture.... the hesitation could come from the o2 sensor too... since its mixture related.... it need about 4 second to send a lean condition !!... if its worn, then could take longer so, my guess is that you hit the gas hard before engaging so you curumpted the o2 so i coulndt it was sending unusual reading(???).... with some adjustement or testing the o2 itself it could be done...

try testing the 02 (cheap to do)
then the AFM (cheap too but harder on fingers)
i dont think the TPS would be really messed up...

RockyB · Nov 24th, 2002, 06:18 PM

I had a similar problem with my car. It drove me nuts trying to figure it out. I replaced my pcv valve, distributor, plugs, wires, coil, o2 sensor, air bypass valve, egr valve, etc. Finally I started checking my vacuum hoses. On the back of my intake manifold was a dried up cracked vacuum hose. It had cracked just enough to stutter at low rpms, but at high rpms it was sealed enough vacuum to stop stuttering. So, check for a vacuum leak. That might be the problem.
Rocky

RiceBox · Nov 24th, 2002, 08:11 PM

I've replaced most of the vacuum hoses but I'll check them again tomorrow

blownb310 · Nov 27th, 2002, 12:33 AM

Ricebox,
My first guess [based on replacing many of them with success], is the air mass meter. You really would be hard pressed to try to test it. The easiest and best way to test it, is to replace it with a known good one. If that's the problem, you will know it immediately. I have an extra one in my tool box for this purpose. Good luck!

RiceBox · Nov 27th, 2002, 09:59 PM

I've been really busy the last few days with school, when I get a chance I'm going to test the air mass meter as it says in the Haynes. If that doesn't work, I'll go buy another one. If it doesn't help the problem, I'll just return it