greetings,

(some of this is a "re-visit")

1).. ok, most people know i have hard starting problems with my 88. so, let me ask a few questions. i am aware that the csv is not "regulated" by the ecm and that the csv is only "active" below a specific temperature. that temperature being "regulated" my the csv temp switch in front of the engine. it has been rather chilly here in florida
(45*) and for the past few days i have had the connector on my csv disconnected. yesterday, i reached in after having not started the cat in a day or so and the car started right up, this w/o the csv being connected. further, when i went to church services yesterday, the car sat for approx 1 hour and when i went to start it it again "required" the pedal to be held to the floor for a faster start but in fact did crank for a bit as usual. now before everyone starts throwing a bunch of stuff at me about pump, plugs, fp, wires, cap, coil, timing, ign module, rotor, relays, csv, csv temp switch, ohming the injectors, leak-down tests, voltage at csv while cranking, etc, i have done or checked, or replace all this and to little avail. now could the radiator temp sensor in the radiator have much to do with the "pulse" or similar of the injectors through the ecm? i realize that sensors will advise the ecm to go into closed loop when the temp is "right" but, do you think it will have anything to do with this "sometimes hard starting when it is cool and hard starting when engine is hot" problem that is chronic with my car? it seems a bit strange that the car would start right up after a day or so w/o having the csv connected.

2)....WITH ALL THINGS BEING EQUAL (driving habits, distance, etc)
(this is a separate question and has nothing to do with
anything written above), if i were to retard the timing on my 88,
what effect would that have on;

a)...gas mileage?...b)...accelleration...c)...the "feeling" of torque?
...or would the ecm "see" the incorrect timing and make "corrections" for it?

....thanks again.

 

I'm not sure how the ECM controls the injectors during cold start except that there is no "enrichment" done, though they may run little stronger due to lower temps.

I think retarding ignition timing would be detremental to all those items mentioned. For best overall performance I would think optimum timing would be required.

For sure launch and power would be down a little. I don't believe the ECM sees total timing, as there is no feedback, so it only reports the advance that it sets in.

 

Your protests to the contrary aside, flooring the gas pedal puts the ECM in the clear flood mode. This shuts off the fuel injectors while you are cranking the engine over. If that makes for easier starting, there is already too much fuel present for the conditions. Leaky injectors come to mind. It isn't a problem after a few days because the excess fuel has time to evaporate.


There is no temp sensor in the radiator.


There are a few things wrong with that paragraph, but the bottom line is that everytime the engine is started, it is in open loop.


2.)
a.) Reduce
b.) Reduce
c.) Reduce
d.) Hotter

The ECM does not "SEE" total timing. The ECM only adds various amounts of timing based on sensing the conditions and responding according to chip/prom programming. If the conditions call for 10° more advance the ECM provides it, but the ECM has no way of knowing if that 10° is being added to the 6° spec base timing, or the 14° base timing I use.

RACE ON!!!

 

....

 

a-ok!

 

?????

RACE ON!!!

 

geez......my responses were in bold type as i am unsure how to copy and past some items here!..

 

I didn't even see the bold print. I didn't write that response very long ago, and I remember what I said, so I ignored it and zipped right past it.
The symptom leads one to reason that there is extra fuel coming from somewhere



Your low coolant sensor doesn't read temperatures and it isn't connected to the ECM. The only sensor that influences starting is the ECT sensor in the front of the intake manifold. I am reasonably sure that the IAT has no impact on the start up fuel mixture.



Yes, that is what I'm saying. There are other conditions that have to be satisfied other than the simple the ECT sensor, to enable closed loop. For one, the O2 has to be hot enough (approx 600° F) to send meaningful data to the ECM. Also, there are timers that have to elapse. Those timers have varying durations, dependent largely on temp, but they don't start running until after the engine is started. Regardless of the engine temp, it starts in open loop.



Good. That is what the forum is for. I'm pleased if I helped.

RACE ON!!!

 

ha!....no problem on the zip right past!...i can't figure how or if extra fuel is getting into the rails at all..(fpr and vac line is clear also). i stand corrected on the temp sensor at front of block. good explanation on the closed loop issue as i surely had it all wrong!...since i bought the car "pre-owned" i have wondered if the injectors have ever been replaced with something larger or if stock. i tend to agree with the extra fuel issue therory because of it being just a bit quicker to start with the pedal to the floor but, have no idea as to why/where. i may have to "cut my loses" so-to-speak and maybe get the injectors rebuilt....and yes, as always, ya did help!...

 

you cannot have "extra fuel" "getting into the rails". The fuel rails are supposed to be 100% full. There should be no room for any more, or extra fuel. The Schrader valve, where you check your fuel pressure is on the fuel rail. It had better be full and up to operating pressure.


The only temp sensor in the block is the oil temperature sending unit, just above the oil filter in the left side of the block, in the rear. The ECT sensor is in the front of the intake manifold, facing toward the front of the car.

RACE ON!!!

 

...agreed. i was just too darn lazy to sign back on and edit my post......my fault......still, i don't know why i have starting issues....(having to hold pedal to floor for faster start)...thanks for reply as always!

 

The only coolant sensor the ECM reads in the CTS in the intake manifold. There is a coolant temperature sender in the right head between #6 and #8 spark plugs that sends coolant temp to the dash guage. The low coolant sensor in the radiator is there to warn you that the coolant level is low, dirty sensor, poor connection, or air in the system.

The CTS only sends resistance values to the ECM depending on engine temp. Cooler engine temp = high resistance & hotter engine temp = low resistance. With a cold engine the ECM uses this information to control fuel delivery, ect (you will notice the engine idles faster with a cold engine). The CTS can be ohmed to check the resistance. In the FSM under code 15 it gives a list of ohm reading depending on engine temps. You can ohm it to easy your mind.

The O2 sensor helps determines open/closed loop. As the exhaust temp rises to ~600* the O2 sensor starts sending voltage reading to the ECM. As CFI-EFI explained and with the accelerator to the floor on start up the refrence pulses are not sent to the injectors (clear flood mode). With the CSV connector off it should have taken longer for the engine to start as max fuel delivery is not achieved for a cold start.

How do the spark plugs look?

Don't go less than 6* BTDC.

 

.....thanks for the additional info!...the car started right up when cold and like i said, after motoring around town a bit and letting the car sit for an hour, it still cranks 3-4 seconds before it starts and again, that is with the pedal being held to the floor. if i don't hold it to the floor, it will crank longer but will eventually start. as you know, the csv temp switch and valve have been replaced and checked to be good also. i have not pulled the plugs but, don't have many miles on them to begin with. i pulled them a few thousand miles ago and checked the gap thinking that it was done incorrectly, and the plugs looked fine. no vac leaks.......i really have nothing left but to ohm the injectors. i hate to try to pull the injectors and have them serviced only to find that they are ok as i suspect. the thing that confuses me is that the car will start faster with pedal to the floor as opposed to not after reaching operating temp, and that the car - currently with the csv disconnected - will start equally as well with "on" as well as with it off....

 

From the description...it sounds like a leaky injector problem.

Try and turn the key on and off a few (2-3) times and try to start the engine without the accelerator to the floor. Sometimes it takes 10 seconds for the ECM to energized the fuel pump relay again.

BTW, is the fuel pump relay working correctly. You can even try to remove the relay and use a short jumper wire in the first pin and the last pin on the fuel pump relay connector and try and start the engine. Simple test.

 

yes, fp relay has been replaced, fp reg is fine, no fuel in vac line, excellent fuel pressure.....i am aware of applying voltage to aldl to activate fuel pump also.....