Help! Crank with delayed start on L98

[TedC]

I'm trying to resolve a delayed or extended start condition on my 1989 L98 (all stock) with 56K. It does this under all conditions; cold, cold restart, hot, hot restart, and hot soak. No fault codes. It always cranks, so I don't think this at all related to VATS. Here is what I've checked out so far. TPS showing .54V at idle and 4.6V at WOT with smooth voltage change between idle/wot/idle using either analog or digital meter. Coolant sensor is showing correct resistance of 7.26K at 41 degrees F. Fuel pressure holds steady at 40.5 PSI during on and start with vacuum line attached. Pressure remains high after shutoff. All 8 multec injectors were replace by the prior owner at a Chevy dealership in 2003 with new multec injectors. All eight injectors measure between 15.8 and 16.2 ohms. The 1989 L98 has no cold start injector. Once started, runs great at all RPMs. Just replaced the cap, rotor, plugs and wires. with AC parts. Old plugs were worn but all showed proper color. I find the best way to start the engine is to crank twice vs. one longer crank. Looking for suggestions on what to check out next. Ignition module? If the EGR was stuck open, shouldn't I see idle issues? One other item that may not be related. If I start the car cold and let it warm up in park, it may stall out (say 1 out of 5 times) when the dash temp reaches the 100-125 degree range. I have not cleaned the IAC.

 

[Tin butcher]

Have you timed how many seconds of cranking it takes before the engine starts? The '89 program has a delayed start so that the engine has oil pressure when it starts, some owners find it annoying. I modified my '85 to run an '89 program. I edited out this delay and now my engine fires immediately. I am thinking of putting the delay back in, I can put up with a slower start if it is going to benefit the engine.

 

[TedC]

I'll time it this weekend and post. I would guess 2-3 seconds. It is not excessive (over 5 seconds). The delayed start program logic makes perfect sense because it does it under all conditions. When measuring engine RPM during a start, it always started just at the point the starter developed maximum cranking RPM, which would produce the best oil pressure.

 

[TedC]

Timed several crank to start times between 1.5 and 2.5 seconds. How much start delay time does the 89 program add over the 85? This added program delay eliminates instant starts, so it appears GM wanted to increase oil pressure during cranking. Would suspect GM issued a TSB on this topic.

 

[Tin butcher]

I never ran my 85 with the unedited program, so I pulled out some notes from when I was studying tuning. "Sometimes it takes 2 to 4 seconds of cranking before the engine will fire. The problem seems to be some missing values in a Crank Fuel PW Multiplier vs Ref Pulse table." This makes it sound like your 89 is working how GM wanted. This thread has been viewed 101 times - funny that other 89 owners have been silent!

 

[TedC]

OK, all L98 C4 owners viewing this thread. Please post year with related crank to start times. Let's see if we can see a trend.
My prior vette was a 1988, with almost instant start times, cold or warm.
Current vette is a 1989, with start times between 1-3 seconds, cold or warm.

Also, does anyone have more info on this TSB?
86-05-02 DEC 98 Warranty - Notice of Delayed Start Process

 

[G Winter]

I have a 90 that I thought cranked to long before starting.I thought I had a problem,but now think it may be programed that way. I have found that if I crank just for a second then crank again it fires quicker.

 

[TedC]

G Winter, I found the double crank trick works on my 1989 as well. One quick crank, wait a second, then crank again and it fires right up. It seems like the first crank starts the delay start process in the ECM. I really thank Tin butcher for pointing this out.

 

[ken mohr]

G Winter, I found the double crank trick works on my 1989 as well. One quick crank, wait a second, then crank again and it fires right up. It seems like the first crank starts the delay start process in the ECM. I really thank Tin butcher for pointing this out.

My 89 is the same!

 

[speedmaster4]

my 86 had ''instant on'' when new, and it was very ''instant''...annoyed me as years of racing have ingrained ''crank for oil before firing''...unplugged the 9th injector and loved 2 sec summer/ 5 sec winter light-off...now have an lt1 intake/ 24 lb lt1 injectors/ no provision for the 9th injector, on it (and other mods tmtl) with l98 oem chip and she starts in half the time as tPi, but ''cold drive-away'' is much better than the tPi.

 

[gmboileau]

Hi
My 90 has the same issue...when hot it often has a delayed start rather than an instant on. Has anyone found a reference to this in the FSM?

Cheers
GAry

 

[Black Bart]

I have a 89 but it has a Accel Gen-7 wide band fuel management system and every thing is set by me in the tables.
I have mine set to start when the engine reaches 375 rpm this takes about 1,5 sec.

 

[89FX3]

My 89 is all stock and has delayed start as well.

 

[CulverC4]

I have an '89 with 152k miles and mine also has a delayed start between 2-3 seconds, all stock. Sometimes though she does start up right away. I'll pay attention to the conditions when this occurs and try to repost soon.

 

[zz4350]

I never ran my 85 with the unedited program, so I pulled out some notes from when I was studying tuning. "Sometimes it takes 2 to 4 seconds of cranking before the engine will fire. The problem seems to be some missing values in a Crank Fuel PW Multiplier vs Ref Pulse table." This makes it sound like your 89 is working how GM wanted. This thread has been viewed 101 times - funny that other 89 owners have been silent!

My 89 also had the longer crank time but I program my own chips and by adding values starting at the 5th reference pulse instead of at the 9th reference pulse in the Crank Fuel PW Multiplier vs Ref Pulse the startup delay is significantly reduced. Unless you are going to have your chip changed you are stuck with the Generals plan which is OK but can be annoying.

 

[TedC]

G Winter's trick does work. Crank twice, first being a very short crank, wait 1-2 seconds, and crank again, and it starts with no delay. Seems like the first crank starts a timer in the ECM. When I had a 1988, it always started without any delays. What is the best way to have a new chip burned?

 

[jmhorn52]

I have an 88 166k miles and it takes about 3-5 seconds to start every once in a while though it starts right up