This may be another shot-in-the-dark, but I remember reading that there is an upgraded MemCal for the '88-'89 cars. Is this true? If so, maybe that's our problem. It would certainly explain why we are all running around changing sensors, relays, ECMs, etc... and not solving our hard start issue.

Again, just a shot-in-the-dark.

 

Burnoff cycle occurs only after car has gone closed loop, then approximately 4 seconds after shutdown for 1 second, so make sure you've run it long enough for this to happen or verify loop status with a scanner. Modified engines with low temp thermostats may not go closed loop at idle. MAF could be bad if it isn't responding to the Burnoff signal; but most problems are in the circuitry, Orange (power) or Black (ground to the ECM driver) wires; high resistance in the Relays; or the ECM. Relays are the same: One is for Power; the other for the Burnoff. The Code 36 chart explains the Burnoff circuit, but without the Code, it's probably of little use in troubleshooting. I don't know of any Memcal changes for the '89 (supposedly, a Bulletin was issued in late '89 about an updated Memcal, but it was applicable to prior years). ECMs were updated due to high circuit board failure rate and when that happened, driveability problems were pretty obvious. Most were replaced under warranty and for those who have never pulled it, you might find that when you do, it's allready been replaced.

 

Thanks for the info, I'll try it out tomorrow. Now that the temperatures here are finally up and above 80 it shouldn't take long for the car to get to closed loop........ Thanks Again........
FRED

 

Okay... here is the latest. I took my car to a local dealer. They have a special corvette shop and a corvette master mechanic. The guy is the gig because he'll talk to you and help you out. Well, he came out to my car and I cranked it up, and yep, it took 2-3 seconds of cranking. He replied, that must be an 88-89. Yep, I replied. He looked under the hood at the injectors and told me that I had the good kind and that the lenght of cranking is right on for these years of vette. He started the car up 7-8 times and told me that the ECM waits for a reference signal from the distributor and sometimes it takes a little more cranking than others to obtain the signal. He also said that there is nothing to replace to fix this. I can attest to this because almost everything involved is NEW!! :lol: So, anyways, after shooting the breeze about a few other items on the car, he told me to hit the road. He did say that there are another model of injectors that were prone to leaking by and end up flooding the engine.... then you end up with a long cranking sequence to get the engine going. I am not sure what he looked at, but he could quickly tell by looking at them if they were that kind or not. Oh well.....

Skip

 

Skip,

This guy starts your car a couple of times and chats you up for a couple of minutes and the issue is gone

What happened to "The engine takes anywhere from 5-8 seconds to start when cranking" ??

Did you ever get a SES code ??

Did your extended cranking only happen under certain circumstances that were not present when this guy looked at your car ??

I'm confused.....

Thanks

 

I have never received a SES light. When the mechanic started the car, it cranked as long as it always has. It did crank longer with the old starter, but it starts faster with the new one. There is a considerable difference from the old starter to the new one... the new one really cranks with a vengance where the old one was a lot slower. I think maybe my time estimation of 5-8 seconds was too long. I have been comparing the car with our two other vehicles that pretty much start as soon as the key is turned. The engine starts anywhere from immediately to 2 seconds. I was concerned about the inconsistancy in starting, and if it was a sign of future problems. Troubleshooting pretty much eliminated possible causes... I would like to see the engine fire immediatly every time... but after reading all the posts on this thread, I get the feeling that I am chasing an elusive dream.

 

This is the email reply that I received from Rich at CruzinPerformance.com when I inquired about getting my injectors cleaned from my ‘89, this is another reason anybody that needs injectors to be cleaned should send them to him, not only does he do excellent work but he is an honest guy, as you can see from his response below. :thumbs:

:thumbs:

 

Also, the mechanic I talked to today cautioned about having the injectors cleaned professionally because the injectors are self-cleaning and the cleaning solutions can damage them. This is something I also read in this forum also.

Skip

 

Thanks for keeping us updated.. I've been following the thread.

What I don't understand is how he says there's no way to fix it. There has to be SOMETHING that is different.. by your description it sounds like it'd be the ECM or distributor. The ECM isn't proprietary to the 88 and 89, and neither is the distributor. What else could it be that's different?

If you don't want to talk to him again and don't mind, could you give us the place's number? Hopefully someone (myself included) could get some more information out of him.

 

Okay, I'll try my best to remember how he explained it... it is something about the pick-up in the distributor. Apparently in the past, the magnetic pick-up on the distributor was so close to the rotating poles that they were sometimes coming in contact, so GM widened the gap. This means that the poles must move faster to send a signal. Also, it sorta sounded like there was a reference pulse, and if the ECM missed the reference pulse, it would have to wait for it to come around again. I am not sure if I explained the last part right... but he specifically stated that this was a 88-89 issue.

 

Multecs are not a faulty design - they are self cleaning - but if you try to clean them or use fuel additives you will have problems.

 

This thread begs the question...how to identify your injectors?

Remember...junior member...handles criticism well...

I'm still new to the TPI. My injectors are black with a yellow stripe or band if I remember correctly. Can't say that I've spent a lot of time just looking at the injectors. But I would like to know more about them. :cool:

 

Checked out the condition with the MAF relay after the car went to closed loop and yes it did glow after I shut the car down, which I suppose means that the MAF relay works and it is still something else. As I mentioned earlier when I replaced the ecm it worked/started perfectly whether hot or cold about 1 half a crank and it would start, morning or night which it also did prior to engine removal/replacement. I also replaced my fuel injectors with new Bosch injectors from TPIS. Thanks again for the help I'll keep trying...... :banghead: :banghead:

 

How about a scientific approach? I am going to time how long it takes to start my car for the next 2-3 days. Then I'll post my results here. I'll time from key turn to engine firing. I'll also note whether the engine was cold or hot. Could some of you do this also? We could compare notes and see what is going on out there.

Skip

 

Sounds like a plan to me...... I can tell you this much, now that it is like 90 + during the day and only down to about 65 at night it hasn't had many problems starting, because it is warm out. Main problem during early spring and late fall when the temps get down in the 40's at night. Right now, usually 3 sec. crank in the morning on the first try, then the next one/two is only about a second, she'll catch and run. In the afternoon on a hot day, usually about 2 seconds first time and instantly if a second is needed. Meaning that the problem has something to do directly with temperature, at least for me. Good Luck guys, I'll keep you posted.
Thanks
FRED :confused:

 

I just talked to my vette mechanic who works for a Chevy dealer and only works on vettes and is sent to the vette school every year. I asked him if 88 and 89 vettes take long cranks to start. He said , "No, they should start right up". If your injectors have a green band , then they have been replaced from the original black band injectors that have a tendancy to leak, causing hard starts. GM replaced the original injectors under warranty. My mechanic replaced my 87's injectors early on while it was still under warranty with the green band ones, they are Lucus, the black bands are Bosch. He said if when it does start, there is a lot of dark smoke in the exhaust, you probably have leaky injectors, otherwise your long cranks are due to being too lean to start immediately.

 

I'll have to get back to this problem later...... Just blew up the tranny again!!! :mad :mad :mad Have to get it fixed before I can drive, and of course had to happen 3/4 of the way to work on the busiest hwy, at the busiest time of the day!!! :mad :mad :mad

 

[QUOTE]How about a scientific approach? I am going to time how long it takes to start my car for the next 2-3 days. Then I'll post my results here. I'll time from key turn to engine firing. I'll also note whether the engine was cold or hot. Could some of you do this also? We could compare notes and see what is going on out there.

Skip[/QUOTE
Too quick to time; hit start & it fires - cold, hot or inbetween.

 

Guys,

I did not read the entire post, but most of it. Let me give a little insight from the tabels that are used for fueling on startup.

There are several that are used to assist in the startup. They are illustrated here with their respective values:



1. Crank Fuel Pulse vs Coolant Temperature. This on supplys the bulk of the PW.

2. Crank pulse width multiplier vs TPS

3. Crank Pulse width multiplier vs crank ref pulse 1-16

4. Crank Pulse width multiplier vs crank ref pulse <17

Ok now that we can see the tables and their values we can further discuss how they work and why some of you might be having problems. Especially after modification to the engine are made. This is assuming that you don't have faulty(leaky injectors) etc.

OK when you hit the ignition the first think the ECM does is determine the coolant temperature for the coolant sensor on the front of the manifold. It then goes to table 1 oulined above (I am not going to write out the names each time, but rather just the respective numbers above). As you see the colder the coolant the more PW that is needed and the more fuel delivered. It then takes that pulse width and goes to the table #2 (TPS) and multiplies the pulse width times that value.....here you can see most all the values are 1.0 so TPS doesn't even effect the fuel delivery, but it effects something else I will soon get to. The ECM then references the tables 3 and 4 which are sent my the distributer as reference pulses. As you crank longer and longer the multiplier gets larger and larger, but becuase its less than 1 its actually cutting back on fuel. Play with the math you will see what I mean. The reason is, as you keep cranking if it did not cut back on the fuel you would drown the engine if it did not start.

Ok now that you have a pretty decent idea how the tables work. Let me explain what some of your poblems might be...more specifically if you altered something in the intake stream, ie MAF screens anything that altered the intake air stream, including the filter etc. People that changed to larger injectors or higher Fuel pressures forget it. These table are all out to lunch and hence your tough starting.

Now let me explain further that its very simple to find out where you are at. Now again it should be expressed that this is butt/u/me-ing that you have do not have leaky injectors, in that case you loose control obviously of what is going on and hence flood the engine, even with the key in the off position.

OK. To see what you are at. If your foot on the gas peddle at startup and the car starts quicker, it not that your adding more fuel, as seen in the table TPS, it your adding more AIR! So that means that you have to compensate the added fuel from the pressure increase or the larger injectors or both. So what I do is decrease the PW adjustment in the coolant temp until you get a crisp clean start. How do I know all this. I have had two engines that would not start after modding and did exactly what you guys all describe. And this is how I cured the problem. Now I can reach through the window and hit the key and within 3 cranks its started.

Remember that the ECM is ignorant, and only as smart as you teach it to be. In a startup situation its only has these tables to go off of. No O2 sensor readings, nothing. So they have to be accurate to have precise starting.

You may say that well my inj are stock and so is the car, but over time my starting has deteriorated. I check the inj and they don't appear to be leaking and hold pressure for 30 min. True and I have a few things that might also cause problems just in the fuel system. 1. Pump might be getting weak at first. 2 FP outputs are VERY much influenced by voltage 3. return line to the tank has a direct and influencial bearing on line pressure/fuel delivery 4. Octane rating and quality of used fuels, definately will influence starting characteristics

Pretty neat stuff when you see what is going on huh?

It should also be said that I'm sure the MAF meter has some bearing on the startup, but I've never see any actual evidence of that. Not to say there isn't. But some items do lead me to believe there is a link. But the main tables that influence the startups are the ones I outlined here.

I need to get Mojo to make some stickies, so these posts do not get lost.

Hope to hear some replies to this.

:cheers:


[Modified by ski_dwn_it, 10:52 AM 6/27/2003]

 

Jeeeesh, glad I typed all that :nonod: :confused: