2QUIK6

On my '95 TA, when the car is cold, it's almost impossible to start. Sometimes I have to flutter the pedal slightly while cranking, sometimes I have to floor it like its flooded, either way, takes 15-20 secs to finally fire and start. Once it's warmed up, it will sometimes crank right off...other times it will crank 5-7 seconds before firing up.

I've put a fuel pressure gauge on it, and it will hold 40# for 30+ minutes after cutting motor off.
FP regulator holds vacuum just fine.

Opti has been changed out twice in the last year and did not seem to fix it.

I'm thinking maybe the Coolant Temp Switch sensor may be bad, but from what I'm reading it supplies the engine temp to the PCM, thatit is not simply an on/off indicator....In which case it would not be bad because my DataMaster is showing the engine temp just fine when hot and cold.

Any other ideas or help is much appreciated.
May start looking at the signal to the coil next, I think I saw something about being able to test it easily, maybe even swap the coil out, but car runs fine once it is started.
Also, just recently passed a sniffer emissions test, and has been hard to start then, but is getting worse. Draining the battery sometimes and needing a jump.

Injuneer

What coolant temp does Datamaster indicate when you are trying to start it cold? Does it match ambient air temp?

"Fluttering" the pedal does nothing other than admit extra air. Flooring it puts it in "clear flood" mode, reducing the injector pulse width. Sure sounds like it's flooding if both those actions tend to shorten the cranking time (although that's not really clear from your description).

And as you figured out, there is no CTS "switch", its a "sensor".

Can you post a link to a Datamster file showing the cold start and engine warm up?

2QUIK6

Couldn't get it started tonight before the battery died. This Optima battery is getting on its last legs anyway, won't hold a charge more than a week. I have a spare in the boat I don't need now so I'll pull it tomorrow and try again. Will also try the various voltage tests on the ignition coil driver wires and opti harness.
Is there a preferred site to post files to?

2QUIK6

Did all of the Ignition coil module tests and all pins have the correct power with key on and cranking, and did the opti harness tests as well, all ok.
Did get the car to start but only after flooring the pedal and pumping it while cranking.
Temp was 58 degrees at startup.
IAC is at 14 at idle.
BLMs are running lean at idle, 136-140, they were on the rich side at 120-122 before I had it emissions tested,so I leaned it out some, got them to 128-132 at 650 rpms idle, but the idle did not seem high enough as it died a few times, so I set idle speed to 750 in the tables and did turn out the idle screw a few turns t get the IAC counts back down and never re-tuned the idle fueling.

Don't have a site to post the DataMaster file, but have it if you want me to email it to you?
Thanks Fred

97WS6SCharged

Are you reading the coolant temp or the idle air temp?

2QUIK6

Engine coolant temp in the top menu bar of DataMaster screen. I think Intake Air Temp is down in one of the blocks in the middle.

97WS6SCharged

I don't recall the layout of Datamaster exactly but if you suspect a bad temp sensor that would be the main one to look at. The engine temp sensor in the waterpump mainly controls the fans though it has some minor effect on fueling also. You haven't wired in any resistors to the iat circuit have you?

Injuneer

E-mail me the Datamaser file. I'll give you my e-mail address via PM.

2QUIK6

I don't suspect the temp sensor being faulty since the temps are being reported on datamaster correctly. The wp temp sensor is the only sensor the PCM sees and is used for fans and startup fueling based on temp and open loop fueling based on temp, and iirc even closed loop fueling adjustments if it gets too hot.

Thanks Fred, i'll send you the DM file this evening when i get in. I ordered a new ICM yesterday just to try that since its the factory original i have.

JFR

I fought with my 95 z28 lt1 for a month. If I floored it and sometimes it would start. Checked fuel pressure, was 37 to 40 lbs when you turned the key on. Kept messing with it, and check fuel pressure again, was 47lbs. My fuel regulator was NOT leaking fuel from the vacumn hose side.
I changed the regulator, wow, started perfect. fuel pressure 31lb to 37lb, checking at different times. 37lb when running.
Fuel pressure was too high and flooding with old fuel regulator, so flooring it to start it did a clear flood and it would start.
So I guess those fuel regulators can be intermitten, I had one.
Hope this helps.
Frank

96flame

What brand of spark plugs? If they are NGK and have been flooded then they are garbage. Try a new set of plugs and see what it does.

2QUIK6

Fred, file sent.
Frank, I really haven't paid much attention to the fp once started, only with key on before cranking. I do need to take a look at it cause I did have to make a slight adjustment to the MAF tables just before having it emissions tested, lowering the fueling at idle because it used to idle right at a 128 BLM and it suddenly was reading 118-120. It started idling very rough periodically and even sometimes dying...
So I leaned out the idle with the MAF tables and upped the idle rpm a little, now it idles with a lean BLM of 136-140 or so... Before it did smell very rich.
It's up on the lift right now with another car under it, I'll move it around tomorrow and loo closer to what it is idling, but it sure is sounding like that could be related to it.

2QUIK6

They are AC Delco Iridiums, were brand new..changed them when I originally found the opti rotor broke, but then the hard to start issue began to happen every so often, they might have 50 miles on them...but yeah, was planning to pull them and inspect them since I don't know what is happening yet, which is why its sitting on the lift now but haven't done it yet.

97WS6SCharged

You didn't try to mess with the plug gaps, did you? Iridium plugs are very brittle and easy to break.

2QUIK6

So 1st time to try to start today, I floored it, then turned the key on to let pump prime, then cranked it..no start of course as no ink should be firing, but as soon as I let off the pedal, it fired up.
Fuel pressure looks within reason, is just a bit high at 40# idling. I shut it right off, no time to heat up any. Fired right up second time, which it usually does after it is started once. So I had already picked up a Ing Coil Module, so I popped the coil assembly off and replaced the ICM, also threw on an old but known good coil I had.
Also, the clasp on the gray coil plug had snapped off some time ago, I had a spare so I replaced it...one time it would not start and I found that it had backed off the plug, so I fixed that with a new gray plug I had ordered a while back.
Put it all back together, it fired right up without any pedal action, but I'm not convinced yet it is fixed....
Also, no fuel coming out of the vac side of the reg. I may still pick up a fp reg since the pressure is a tad high, it is 18 years old so it couldn't hurt.
Stay tuned...