cold start problem - need help!

yes, those hoses look original on my car, despite so many other things being replaced. they look normal from the outside, but i can easily replace.thanks for the advice

 

for the brave souls who have been following my saga, here is my current plan:
1. disconnect and cap off the vacuum lines to the reservoir canister and the brake booster (although the booster line T's into a fitting on the rear of the 7-12 head cam cover - which i think is a vacuum pump) to eliminate possibility of vacuum leaks in those systems
2. replace air lines from auxiliary air valves to intakes (looks like original braided Cohline branded hose - seem fine but easy to replace)
3. buy a good quality voltmeter (since my "Klein" unit seems sketchy at best)

try again to measure voltage off the O2 sensors and adjust the idle mixture. Since the engine was supposedly tuned with the protection relay not working, it makes sense that the underlying problem may be poor setting of mixture screws. we will see

of course, i still have a defective thermal time switch for the cold injectors, but i have a new one on order, and as best as I can understand, that shouldnt have any affect on idle tuning when the engine is warm. Ironically, the engine idles right at 1000 rpm when started cold (ambient temps mid 50's). As it warms up, the idle creeps up to 1400 rpm. i guess the reverse would be the goal!

 

can you screw the wideband sensors into the fittings for the stock narrow O2 sensors? that would make it easy to use, once you get over the expense of the dual wideband system

 

An update to my idling and tuning problem -- i bought a more reliabel multimeter (Fluke 117). Although it is supposed to be able to give me an accurate reading on engine rpm (to see how far the dash tach is off), I have not been able to make that work yet. But i did get more accurate readings off the O2 sensors. i found my car was set too rich (makes sense, since the protection relay, and thus the EHA system was not working when the car was tuned). By turning the fuel mixture screws outward more than half a turn, i got the O2 sensor output voltage to read about 0.7. Once I did that, i was able to turn back the throttle position screws to get the car to idle below 1000 rpm with the air bypass screws all the way closed down.
Then I got exhausted from all the exhaust blowing in my face, and it started snowing again (new York), so i stopped for today. Although I have to work for the next 6 days in a row, my next steps are to replace the thermo time switch (i got a new one, which seems to work properly based on the resistance reading across its terminals even after i dropped it 4 feet off my bench onto concrete floor). and see if I can improve this cold-start dilemma!

thanks everyone for support. i hope to report back in a week or two with success.

justin

 

replacing the thermo-time switch:
with my cold start trouble, when I checked resistance on the leads for the thermotime switch (TTS), one of the leads read infinite resistance consistently, over and over again, so i assumed it was defective. so I ordered a new (NOS old stock) TTS and got up the nerve to change it. My fear was that coolant would spill all over the beautiful clean front of the engine. My plan was to :
keep expansion tank cap in place so maybe there would be some kind of vacuum to limit fluid flow. stuff paper towels all around the sensor to soak up fluid flow. then get up courage and remove it, with the new replacement TTS ready to drop right in.

here is how it went:
used a large socket to break it loose;
like a lunatic, i rushed to get it out. i saw the copper washer stayed behind, so i had to panic to find that so that I would not put a new switch in with 2 washers in place. in the midst of my lunacy, I noticed no coolant was spilling out. this was weird. there seemed to be coolant in there, but for some reason, none was spilling out. so I put the new TTS in, tightened it up, and smiled. The cooling system does seem to be full, so I am not entirely sure why no fluid came out. maybe the TTS is at the top of the coolant system? the expansion tank is higher, so I dont know.

i was really happy until i checked the resistance across the terminals of the old TTS once out of the car just for fun. and now both terminals are reading proper resistance (60ohms for one and a couple ohms for the other). Not sure if this was just unnecessary, or if maybe the old TTS has poor connections inside and the act of torquing it out re-established the connections. i guess we will see next time i start it up and get it running

Anyway, the point of this story is that our experts Steve and Rifledriver were correct (as always, you dont need to remind me) that changing the TTS in place would not make a mess of coolant.

 

this may be the happy conclusion to this long post.

i replaced the thermo time switch (I also replaced the defective protection relay last week)
After leaning out the throttle mixture screws, and following normal idle balancing and mixture adjustments, i think things are running really well!

idle with air bypass screws turned all the way in: 800 rpm (maybe 850 really)
idle with bypass screws opened just a little bit: 1000 rpm
vacuum on both intake manifolds identical
O2 sensors reading about 0.7 volts on both sides

cold start was great! cranked, started, and immediately idled at 1000 rpm.

thanks so much to the helpful friends here at Fchat.

key learning points:
1. check the protection relay (protocol outlined by Steve in the early phases of this long post)
2. learn that fuel mixture screws will make big difference with small amount of adjustment when in the sweet spot of the O2 sensors (0.4 to 0.7 volts). out of that range, may need to turn the screws a lot to get back into range
3. if an engine is setup with a defective protection relay, then the engine will be very rich once the relay is repaired
4. helpful advisors at Fchat = priceless!

 

EDIT to previous post- in the highly unusualy case that anyone is using my posts as a guide. the idle with air bypass screws turned all the way in was set to about 750rpm, not 850. then i turned the air bypass screws out about a quarter of a turn, which brought the idle to 1000rpm. vacuum on both banks is equal bot at 750 and at 1000 rpm.

i did have to loosen the idle throttle microswitch, so that it did not block adjustments of the passenger side throttle body. And i also had to detach the cross-linkage from one of the throttle bodies, so that i could adjust each throttle body idle set screw independently. All of this is standard procedure if you follow the shop manual or steve's helpful documents outlining the procedure

Another helpful side note -- the O2 sensors do take a while to warm up and give consistent readings - a lot more than the few seconds I thought it would take

 

OK, i thought this post was done, but I am running into a problem with the throttle microswitch
If I set up idle and tune with the microswitch plug jumped appropriately, things go well and if I pull the jumper wire, the idle increase about 200 rpm, just as it is supposed to

I adjusted the microswitch so that is just clicks as the throttle comes off idle, which i think is exactly as it is supposed to. But when I run the car with it connected, once the car warms up, the idle is about 1250rpm. If I loosen the screws for the microswitch, the idle will come up or down, as if it is making intermittent contact. I am thinking the switch must be bad. i guess i will pull it off and look at it - maybe buy a new one.

I cant quite tell from forum searches - is it common for this switch to go bad over time? A little frustrating that this car which just came from a huge mechanical restoration, would have defective thermo time switch, protection relay, and throttle switch. although i dont think the car really had time for a proper sorting afterthe work was done

 

I also find that, when engine cold, if i give it throttle and then let go of throttle, the rpms drops very low and the engine will stall. i wonder if this is part of the same problem

 

i replaced the throttle microswitch with a new one. things are good now!!
the original throttle switch was temperamental at the idle switch (works fine on bench but not in car), but did not give any signal for wide open throttle

the replacement I bought is made by Vemo- i was a bit concerned at first with potential quality, but it is made in Italy! and so far, for one day, it has worked flawlessly, although I am at the end of adjustment to get it right, so i can not turn down my idle screws any lower.

On other news, as my engine warms up, the idle creeps up to 1150rpm. I could turn down the air bypass screws some more, but I am concerned it wont run as well when not fully warmed up. I am going to put some miles on it first, before any more judgements, since I have not run it out of my driveway yet

I wish there was a way to get more out of the cold-start warm up circuits (I guess that would be the Aux air valves on the US KE Jetronic). From what I understand, those are closed within a minute or so of cold starting. Steve hinted there might be some adjustment but I dont see that anywhere