I've been wrestling with a mostly dead '04 D2 (HSE with SAI and 190K miles, complete engine rebuild at ~125K miles) for the past 6 weeks.

Mostly dead, because it will start, rev momentarily up to 2,500-4,000 rpm on its own, i.e., no throttle, then drop to 200-300rpm, stumble along for a few more seconds, then die.

Other symptoms/observations leading up to current situation:

• Threw a MAF sensor code in March or so (drove that way for 6 months, replaced MAF with Bosch version as part of current troubleshooting);
• In early October, it started to exhibit "limp home" type of behavior: it would lose power, die unless throttle was feathered, then behave normally, sometimes for extended periods;
• In late October, it got progressively worse, then finally died completely, has only exhibited the momentarily start then die behavior, since
• SAI seemed to not be running for last month or so before totally dying (I know the SAI runs only under certain conditions, but usually at startup in warm weather but not for month or so)

Even though the tachometer was responsive, I replaced the CPS anyway (what a PITA with the engine in-place).

I have a fuel pressure gauge on the fuel rail schraeder, and it registers 50psi when cranking, drops below 40psi after momentarily running.

Some folks have suggested that maybe I have blocked cat converters and suggested I open up the exhaust at the exhaust manifold flange, but given that it runs, at least momentarily, I am not going down this route yet.

Also, at the suggestion of one forum member, I also tried starting the D2 with the MAF sensor disconnected, and the behavior was the same.

The beast is sitting in front of my house (I have a 30-40% grade driveway down and am worried if I roll it down there, I'll never get it back up), so a little limited in what I can do.

In lieu of any advice here, my next "throwing parts at it" step is likely to be a new fuel pump as it just feels to me like a fuel delivery problem (FYI, I also replaced the coil packs even though spark doesn't seen to be the issue as they were original with 190K miles on it).

 

SAI fuel pumps are cheap on D2's last one I bought was 43.00 on ebay for the entire assembly.

 

Used pump, I presume?

So could it be the pressure regulator (it's built into the pump, right?). It wouldn't be that I have a venting issue, so as the pump runs, it begins to pull a vacuum in the tank and chokes off fuel flow? I've tried to study the fuel vapor recirculation and venting system on the D2 from the RAV, and trying to understand it makes my head spin.

FYI, no used D2 SAI fuel pumps on eBay at moment that I could find.

While on SAI, also I tested the SAI pump (put 12v to it) and it runs fine when 12v is put to, just not it seems when it connected to the harness.

 

I think I suggested the MAF. Having tried it disconnected you can rule that out. I suspect a bad IAV, you can try disconnecting it but you will need to hold the throttle open while starting. You may also have a vacuum leak somewhere, you may want to check that first.

 

Hmm. I actually have a spare IAC valve (picked it up at a junkyard, was planning on throwing it away, good thing I didn't), so I'll swap it in tomorrow.

Interestingly, when I was under the hood today, with the ignition in "run" position (to see if the fuel rail pressurized), I happened to put my hand on the plastic intake pipe and felt a "hum" that I traced to the throttle body and then to the IACV. It was energized/vibrating.

I am guessing that the IAC valve is supposed to either open or close like a solenoid but not "oscillate" rapidly to create that hum/vibration -- or maybe it is stuck in one position and and trying to change to the other, which is causing the vibration.

Am I right that a humming/vibrating IACV is not correct? Is the IAC valve fused and/or relayed?

 

My best guess would be fuel pump, since pressure is dropping once started.

The vacuum leak theory is a possibility, but it would have to be substantial...so it would have to be one of the larger ports on intake manifold. Did you notice any brake issues before, like lack of power assist, when running issue happening randomly?

 

No brake assist issues when it was still running -- though after it died and I had to tow it back to home without the assist -- about 10-15 miles thru Texas Hill Country -- it took all the effort I could muster to stop the beast once it got rolling. That's another reason I am afraid to roll it down my driveway: I am worried I won't be able to stop it.

I was think maybe something in the evap/ vapor venting system but in reading RAV it appears that the evap system has safeguards against a vacuum situation in the fuel delivery system itself?

The fuel rail pressure drops only a bit once cranking stops -- from 50-51psi (spec is 52psi) to 42-45psi -- which indicates the check valve or something else is not maintaining pressure. I'll check again.

But I am starting with IAC valve first today as it was humming with the key in the II position as RAV says that a failed IAC could cause stalling. It's a 5 min test, and I have a known good spare.(From RAV) In the event of an IACV signal failure any of the following symptoms may be observed:

l Either low or high idle speed. (it revs unusually high -- 4,000+ rpm -- and stays there for several seconds when it starts)

l Engine stalls. (it stalls once it drops from 4,000ish to 200-300 rpm)

l Difficult starting.

l Idle speed in default condition.

 

Yeah, that sounds like a good starting point. Plus, it's an easy swap.

 

IAC hums normally, but it still might be stuck open.. If swap does not fix it try starting with throttle open a little with your foot, or open it after it starts.

 

Was thinking about this a bit more and if memory serves me right...when l drowned my 01, sucking dirt and water through air filter and into throttle body and manifold. Afterwards, the 01 did a similar event, starting and idling up to 2500/3000 rpm and then dropping off on it's own. The MAF got destroyed, naturally, during drowning and l changed that prior to the idle control valve. The MAF solved some other issues, no acceleration, but still had high reving on start up. Swapped idle control and it correct high idle issue. It was full of water and gravel though. Granted, l don't remember mine stalling...just reving up...then eventually came down to proper idle.
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