cold hesitation
#16
bummer, running out of low hanging fruit, the ICV or whatever it is has it connector on, not sure what if anything this one is for, I tried to pressurize the intake (looking for vacuum leaks) but I think I need engine at TDC because the air is just going straight out the intake valves, or so it sounds, I think I'll curl up under the dash with a multimeter and start checking components via the DME connector......
#17
hmmm, unused connector for Auxillary Air Valve on early 944, not present on 924s, but we've got a '83 944 engine, an '87 924s body and have replaced the harness......will keep searching
http://forums.pelicanparts.com/porsc...what-heck.html
http://forums.pelicanparts.com/porsc...what-heck.html
#18
Okay, round of testing:
Temp sensor cold: in spec
Temp sensor hot: in spec
TPS; off idle: good
WOT: pedal would not activate. It grounded against a stop screw under the pedal before it reached WOT, manually moving throttle it tripped the switch
Ran the stop screw a few turns further down (to allow pedal to travel down more) and WOT signal.
Put on fuel pressure gauge; shoots to 29 instantly, hold steady during idle but drops down to 10 on shut down and bleed down pretty quickly BUT we found a pin hole in the fuel hose where it transitions from the filter over to the hard line, that could explain the rapid bleed off
Also running original higher pressure expansion cap, no bubbles in coolant, fans kicked in when temp reached no drama now here's the deal:
During testing, the idle got rough (while still quite cold) just like we were experiencing on the road, she didn't want to rev, fuel pressure was still 29, idle would often fluctuate, up to 2000 then down as I tickled the throttle (by hand in engine bay) then I noticed the throttle piece that the return spring is attached to wasn't retracting fully, sometimes it would pull it back all the way, (and the idle would drop to normal) sometimes not, easy fix; tighten spring a few coils, revs and return to idle were completely stablized. Problem found?? a loose spring? could it be that easy?
Temp sensor cold: in spec
Temp sensor hot: in spec
TPS; off idle: good
WOT: pedal would not activate. It grounded against a stop screw under the pedal before it reached WOT, manually moving throttle it tripped the switch
Ran the stop screw a few turns further down (to allow pedal to travel down more) and WOT signal.
Put on fuel pressure gauge; shoots to 29 instantly, hold steady during idle but drops down to 10 on shut down and bleed down pretty quickly BUT we found a pin hole in the fuel hose where it transitions from the filter over to the hard line, that could explain the rapid bleed off
Also running original higher pressure expansion cap, no bubbles in coolant, fans kicked in when temp reached no drama now here's the deal:
During testing, the idle got rough (while still quite cold) just like we were experiencing on the road, she didn't want to rev, fuel pressure was still 29, idle would often fluctuate, up to 2000 then down as I tickled the throttle (by hand in engine bay) then I noticed the throttle piece that the return spring is attached to wasn't retracting fully, sometimes it would pull it back all the way, (and the idle would drop to normal) sometimes not, easy fix; tighten spring a few coils, revs and return to idle were completely stablized. Problem found?? a loose spring? could it be that easy?
#20
I don't know man, 135-140psi across all 4 cylinders, I hate to go after a HG that's perfectly happy. Started with expansion cap off to see if there were pressure or bubbles, nothing, ran it up to temp, all good, took a short drive, okay, temp good, fan on, running fine. Shut down pulled all four plugs, held open throttle cranked over with compression tester on #4 until no more climb: 140 psi, same for #3, #2 and #1 were a bit lower but the battery was getting pissed by then and turning over slower. Weird.
#21
Tested AFM as per clark's, seems okay although it's receiving 5v and putting out only 4 when flap is at max, should be closer to the input voltage of 5, no idea how significant that is, not much.
So it still does exactly the same thing; starts idles fine but at some point very early in the run it looses all power, have to limp down the road, clutch and gas will raise rpm but trying to put power back on, no joy, then suddenly, and you can hear it, it clears and off you go, it won't return again until the car goes cold.
What the heck is that unsed EV1 plug for? This harness should not have a knock sensor I don't think (early 944 engine in it so it doesn't have the sensor in the head)
So it still does exactly the same thing; starts idles fine but at some point very early in the run it looses all power, have to limp down the road, clutch and gas will raise rpm but trying to put power back on, no joy, then suddenly, and you can hear it, it clears and off you go, it won't return again until the car goes cold.
What the heck is that unsed EV1 plug for? This harness should not have a knock sensor I don't think (early 944 engine in it so it doesn't have the sensor in the head)
#23
We checked our added pre-pump filter, looked pretty nasty, replaced, it made no difference. Didn't do flow test simply because it's a PITA to trick the pump into running, will make a jumper for the relay or maybe just hit the pump itself with 12v. It's very weird that it ALWAYS happens and ALWAYS clears itself the same way, has to be electrical/sensor/DME, doesn't it? Something mechanical/vacuum related couldn't be so regular I wouldn't think.
I'm going to throw in a new DME temp sensor even though it passed the test. I just don't know what else to do at this point.
I'm going to throw in a new DME temp sensor even though it passed the test. I just don't know what else to do at this point.
#24
New sensor in. Same deal, in fact it was worse than ever, got about 300 ft from the shop, headed right back, thought I'd disconnect the O2 sensor while it was acting up, opened the hood, it was running VERY rough, never this bad before, like it was on 2 cylinders, so I wiggled plug wires then grabbed the distributor, as soon as I touched it she smoothed right out, coincidence? Perhaps. I immediately jumped in and joy rode around town, never missed a beat. I'll pull the dist. cap and look, maybe coil wire, the car had a seriously corroded coil wire when we got it (since replaced of course).
#26
fired up, let idle, about 3 minutes in it started to stumble, right on cue, unplugged O2 sensor, idle hunted a bit then smoothed out. Will run some tests. It's only got a couple hundred miles on it.
#27
Put old sensor back (I'm a pack rat). Car did not exhibit symptoms. Looks like it was o2 sensor all along, well, pending further testing. I timed it, stumble occurred almost exactly at 90 seconds which is when the DME looks at it for info.
#30
Rainman
Rennlist Member
Rennlist Member
O2 sensor reading isn't used when engine is cold though. But yes you're supposed to crimp those not solder.
You mentioned a mix and match of 83 engine with 87 body.
Are you sure the AFM and DME are compatible based on model years?
You mentioned a mix and match of 83 engine with 87 body.
Are you sure the AFM and DME are compatible based on model years?