Automobiles Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
237 Posts
Discussion Starter · #1 ·
Howdy all,

I've already posted this on the qsw list but thought i'd try my luck here as you all are the i5 pros.. :

I finally got my Quantum sedan ('88 5cyl cis-e) back together after a year and a half of sitting in my shop while I slowly picked away at a ton of various projects on her.. Some of which included: All new fuel and brake lines, new fuel pressure accumulator & fuel filter, new heater core, converted the rear drums to disks w/ Al mkiv calipers, new water pump & timing belt, new muffler, some minor rust repairs, new headliner, and surely a number of other things I can'€™t remember back to at the moment..

So my issue is poor starting, running, and hesitation. Mind you that the car ran fine when It was regularly driven before I parked it 1.5+ years ago for all this work.. Basically the car cranks longer then It should (5-10 seconds) and then does fire-up but barely maintains an idle, around 4-500 rpms, it sounds like its gonna stall but doesn't, after a minute or so it will idle a bit higher but will almost stall if you give it any gas, eventually it will idle slightly more normal (~750rpms) after a very thorough warm up (5+ minutes). Once it'€™s Fully warmed up its drivable but with substantial power loss and lots of hesitation.

Things ive checked/done so far:
-all new gas, (I drained the tank prior to doing the fuel line work, so its all fresh..)
-triple checked crank/cam timing
-ignition timing properly set at 6deg specs (cap and rotor look ok)
-no obvious air leaks or unplugged vac hoses
-fairly new injector seals
-its hot out now here in Pa now so the cold start valve shouldn't be an issue..
-checked air filter box for nests..
-disconnected ISV connector with no change in idle

I know there'€™s a lot more possibilities to look into but I thought I would post here first to try and save myself some unnecessary diagnosis time if there's some obvious things I should check first.. So what next-? fuel pressure test? O2 sensor? Fuel distributor/fpr (don'€™t have a spare to easily swap out with though unless i pull it from my qsw..)? what other cis junk should i check? Any help much appreciated!

Thanks a lot :cheers:

Jason
 

·
Registered
Joined
·
991 Posts
I'd still do a thorough vacuum leak test, preferably with smoke (I use a cheap cigar from the gas station blown into a vacuum line). Since you mentioned no "obvious" leaks, I'll present to you the rotted vacuum line I found yesterday:



I slit open the fabric to see why smoke was seeping out of the pores, and that's what I found. The fabric was hiding the complete disintegration of the rubber. I never would have found that with a visual inspection, since it looked fine from the outside.

Completely rule out a vacuum leak, and then you can move on to the harder, more expensive stuff.

-Rog
 

·
Registered
Joined
·
237 Posts
Discussion Starter · #3 ·
Yea, I know I gotta rule that out for sure..

how do you blow the cigar smoke into the lines?
 

·
Registered
Joined
·
7,425 Posts
Check the coolant temperature sensor at the front of the motor, drivers side. Should be 2 sensors, the top one is for the temp gauge, but the bottom one controls the mixture. Sounds like a classic sign that the sensor is faulty. You could always test it by unplugging the sensor and seeing if it helps get the car started (just dont leave it disconnected all the time).
 

·
Registered
Joined
·
991 Posts
jlw said:
Yea, I know I gotta rule that out for sure..

how do you blow the cigar smoke into the lines?
Just take a line loose and blow smoke into it. You don't have to inhale of course. ;)

For a non-turbo engine it usually only takes a puff or two before you start seeing a leak, if there is any.

-Rog
 

·
Registered
Joined
·
237 Posts
Discussion Starter · #6 ·
Rogviler said:
jlw said:
Yea, I know I gotta rule that out for sure..

how do you blow the cigar smoke into the lines?
Just take a line loose and blow smoke into it. You don't have to inhale of course. ;)

For a non-turbo engine it usually only takes a puff or two before you start seeing a leak, if there is any.

-Rog
hahah, I guess i over thought that one..

Will give it a try in the am, gonna dig into it again tomorrow.. Thanks
 

·
Registered
Joined
·
237 Posts
Discussion Starter · #7 ·
AudiSport4000 said:
Check the coolant temperature sensor at the front of the motor, drivers side. Should be 2 sensors, the top one is for the temp gauge, but the bottom one controls the mixture. Sounds like a classic sign that the sensor is faulty. You could always test it by unplugging the sensor and seeing if it helps get the car started (just dont leave it disconnected all the time).
-- disconnecting this didnt effect anything.. I also tested its resisance as per bently and its within specs. Just in case though Im gonna try swapping it out for a spare i have once i can dig it up..

So I've been tinkering around on it all morning with no real luck. I am almost completely certain that there are no air/vac leaks that would contribute to it running this poorly. I removed all intake plumbing and really looked over things, as well as spraying carb cleaner and tried propane with it idling, to try and effect rpms, with no response.

I also jumpered the fuel pump and lifted up on the metering plate in the intake, and could hear injectors spraying. I didnt pull any injectors to measure volume or pressure, but atleast i can say some of/all of them are spraying somethings..

I'm beginning to get frustrated..

For some reason I'm leaning towards a fuel delivery problem.. The first start from dead cold each time, it fires right up for a second or two then dies. Im assuming this is it just running on cold start injector spray? This point to anything to anyone??

I'm thinking about pulling the entire fuel distributor/frp assembly from my good running QSW and swapping it into the sedan in order to rule that out or not.. But im dreading the mess of undoing pressurized fuel lines on both cars... Think that's worth a shot ??

Im racking my brain trying to think of what other potentially faulty sensor would make it run this badly.. ?

Any more suggestions very welcome! Thanks,

J
 

·
Registered
Joined
·
237 Posts
Discussion Starter · #8 ·
AudiSport4000 said:
Check the coolant temperature sensor at the front of the motor, drivers side. Should be 2 sensors, the top one is for the temp gauge, but the bottom one controls the mixture. Sounds like a classic sign that the sensor is faulty. You could always test it by unplugging the sensor and seeing if it helps get the car started (just dont leave it disconnected all the time).
-- I did swap out the oxs coolant sensor with a new one i forgot i had kicking around.. no change..

After that I did go ahead and pull the fuel distrib/fpr/meter-plate assembly from my working syncro and installed it on the sedan and..... it wont even fire up at all now! it stumbles a bit like its trying to, but never really catches... weird..

I also tried a another ICM for shits and giggles... no change..

I'm done with it for today.. i guess im gonna swap the distribs back in the am and go back to the drawing board..
 
1 - 8 of 8 Posts
Top