Re: Starting problem.. 1989 C4 (ski_dwn_it)
 

One Quick ????, How does one adjust the PW in the car??? Thanks for the info, I'll iron out the start-up, but first I have to fix my blown tranny. Died this am on the way to work. :mad :mad

Re: Starting problem.. 1989 C4 (ONEBAD89)
 

The PW is adjusted via the chip with reprogramming. That is the crappy thing. Its not an easy thing to do unless your setup for doing chips. :banghead:

But I assure you that is the problems with many of the cars here that won't start. As I said the ECM is only as smart as you teach it to be. :cheers:

Re: Starting problem.. 1989 C4 (ski_dwn_it)
 

So ski-dwn-it, let me see if I understand: what you are saying is that any of us that have any modification to our cars that are intended to increase the incoming airflow will potentially suffer from a hard-start condition because of too short a pulse-width during start-up. Is this correct - am I reading your posts right?

I am no doubting you in anyway. My '89 suffers from this, and has for a while now. The car is virtually stock with the exception of a cut-lid, K&N filter, and MAF screens removed. I replaced my original injectors about 2 years ago with a set of 'blue-streak' injectors - these are a stock replacement injector, not a performance type or anything. I don't think my injectors are leaking because the fuel system hold 40psi of pressure quite well prior to startup. But other than what I've mentioned, the car is stock. Do you think that just with these small mods to my car's intake that the pulse-width is not enough? I mean Corvette guys put cut lids and de-screened MAFs on these cars all the time and you never hear of any hard-starting problems. Why on the '88-'89 cars?

But thanks for all the great info.


[Modified by TheCorvetteKid, 4:49 PM 6/27/2003]

Re: Starting problem.. 1989 C4 (TheCorvetteKid)
 

CorvetteKid,

The key word you used is potentially. I can't say for sure that every engine is going to react in the same manner to every mod. But I can tell you, that alterning the incoming air path on these cars most definately screws with the initial tune. Then add on to that all the other items I meantioned and you now have the "hard start" problem. I have been thinking about the MAF in this scenerio all last night after posting this and I'm sure that it has an effect, as does the IAC on it as well.

But I can tell you both my engines did exactly what you all describe after mods and this is how I fixed it. I had the injectors changed to larger ones too. So in my case I needed to reduce the PW in the coolant table, since the stock ones were previously setup for stock (smaller) injectors.

As I said if you crack the TB open with the gas peddle ~1/4-1/2 way, and the car starts bette, chances are its getting tooo much fuel with no gas peddle. So you , like me, will have to decrease the PW at that particular cell unit you get the desired results.

The whole sorting out of the problem is really a trial and error type scenerio. With the use of Romulator, it can be easily done in a matter of a <10 minutes.

But I would be willing to bet that 90% of the problems mentioned here could be solved with this method.

Its key to remember that all these setting are setup with a particular pressure, injectors, spark plugs, spark advance (mainly base), etc. If you change one of them the entire balance is messed up. Change a few of them, as many of us do, and you have a nightmare.

Re: Starting problem.. 1989 C4 (TheCorvetteKid)
 

Im glad Im not the only one with this problem, I too replaced Everything in my 89, including the 2 MAF relays, I also swapped my ECM, still wont start when cold, it takes an embarrasingly long time cranking to get it started, I do all the work myself, I finally brought it to my friends shop, he cant find the problem, everything checks out OK, no codes, fuel system great etc,etc!!. The only thing I havent changed is the oil pressure switch, its really hard to think that will fix it, I am spending too much time and money on all this troubleshooting, Im ready to burn the car!! lol, I hope we can all put our heads together and figure this out! :auto:

Re: Starting problem.. 1989 C4 (Anotheredvette)
 

What is there to figure out? I just told you what the problem is :banghead:

Re: Starting problem.. 1989 C4 (ski_dwn_it)
 

ski_dwn_it,

Thanks for the info, you have been very usefull, but a couple quick questions:
1- My hard start-up is directly related to temperature: cold-PIA, warm-not bad and hot-easy. Will adjusting the PW help?
2- Why did the car start correctly for 2 weeks regardless of temp after I replaced the ecm?
3- How long is the fuel pressure supposed to remain at what I set it at? I attached the fuel pressure gauge and by morning the fp wa down to 0, but with the turning of the key was right back to 42, where I set it.

Again, thanks for all the info, look forward to your reply.
P.S. What is the romulator??? :confused:

Re: Starting problem.. 1989 C4 (TheCorvetteKid)
 

I'm with JFB.

Buy/borrow a fuel pressure gauge. The Sears Actron model even has the bypass button for a fuel volume flow check.

Fuel pressure/flow, values needed for proper diagnostics.

After getting the fuel numbers analyzed, I would head for the ignition module. Those darn things have some timing built in till the 400 RPM level when the ECM takes over timing. Could be a problem there. The modules are generally very reliable but perform several important functions. I would have that tested(ignition module), at two different places with reliable test equipment.

Tough problem for sure.

dlmeyers 90 coupe zf6 3 speed shocks

Re: Starting problem.. 1989 C4 (ski_dwn_it)
 

OK, I get the picture, but now we have to find someone who can re program our proms. Who, where and how much? I am willing to try anything at this point! Im sure everyone else is also! Please Help! :auto:

Re: Starting problem.. 1989 C4 (Anotheredvette)
 

Redvette.

No not necessarily. Either post or explain thus far what you have done to the car, by means to correct/check the fuel supply. I can make some suggestions and see if you get any decent results. I will probably help some others also.

List any mods you have done....etc :cheers:

Re: Starting problem.. 1989 C4 (SkipI)
 

Okay, I have been timing my starts and have come up with the following. The average of my starts is 1.7-2.0 seconds from key turn to key turn. It is pretty consistant around this time frame.

Now, I have a question.... there have been a few posts here about coolant temp. According to my factory service manual, the temp sensor used by the ECM is the one in front of the throttle body... and that one I recently replaced. But what is the one on the passenger side of the block in between the back two spark plugs for?? Also, which one indicates on on the dash?

Skip

Re: Starting problem.. 1989 C4 (SkipI)
 

Check out this thread:

http://forums.corvetteforum.com/zerothread?id=575989

There is lots of valuable information about the coolant sensors in there.

For the record, when my 88 is hot it starts as soon as I touch the key. When it's cold it takes about 3 seconds to start. What's weird is I have very leaky injectors, so I'd expect the opposite. In any case I'm going to replace them in the next week.

Re: Starting problem.. 1989 C4 (SkipI)
 

In regards to the temp sensors, on my 89: the front of the manifold under the TB controls fuel/talks to ecm at start-up, passenger side displays on the dash the coolant temp and the drivers side controls the fan. Good luck with yours, I will be taking my down to LevelTen Transmission shop Friday to fix the tranny again, then I'll get back to the startup problem.

FRED

It seams like a great deal of us have problems with our 89 vettes starting hot. This must be a design flaw. I think we should go after Chevrolet and make them fix this problem as a recall. Any one else have any thoughts on the matter?

Starting problem - 1989 C4
 

Well a lot of info here. Hope I can find the right answer. Car was running great. Parked it and when I tried to start next day it coughed and then no start. Smelled raw fuel. Engine acted as if it was flooded. Have not done any trouble shooting yet other than try several re-starts. With throttle wide open before truning crank it makes a slightly better attempt to start but still no start.I will replace the in-line fuel filter just as a maintenance issue since I'm sure it is original (64,000 mi.). Since I can smell raw fuel I am leaning towards stuck injector. This my first Corvette and have always wanted one but just couldn't justify a new one, bought SS Blazer with the 395hp aluminum motor instead. This car is faster than the 89 but not quite as "cool". Hopeful for succesful fix on the Corvette. If anyone has new info I would love to see it.
Thanks in advance

Starting Problems abound
 

I've an 87 with the same prob more or less like yours. Bought & brought home a 87 Convert...oil level was over full & smelled of gas, but car ran Ok, but a little rough...knew the injectors were at fault (or some were leaking) replaced all 8 with new Bosch. After everything back together, oil changed etc., it won't start. Fuel pressure is about 45lbs, stays for a few minutes & slowly falls to almost 10lbs or so. After reading all these posts, I'm more lost than ever! Will try disconnecting the MAF in the am & see if it will start. Seems like the fan starts as soon as the key is on, think that is not right, fan shouldn't come on 'til it's warmed up. Could be some of the sensors have crapped out sitting for a month in my garage with batt disconnected? I have my doubts. I'll post my results.

Thanks for your note Peco. I have now learned that engine will start if I spray some starter fluid in the throttle body opening, removed the MAF hose to do this, but as soon as the strater fluid burns off engine quits. I would think this means I have a fuel delivery problem. Also removed the cap on the test port(scharder valve) on the fuel rail and nothing came out when I depressed the the valve stem. I had cranked the engine for about 30 seconds before doing this. I would have thought there would have been fuel pressure here. I am changing the fuel filter Thursday but I think the in tank pump may be bad.

Starting problem - 1989 C4
 

You are correct, should have been fuel at the valve. I did the same thing, same no start results, but I'd bought a fuel injection pressure gauge set from Harbor Freight, on sale for 19.99 & my system shows 42 lbs when key is on...drops into the lo 30's - hi 20's when cranking. Drops to lo 20's within a few minutes when key is off. Injectors leaking or ?? I've touched the injectors while cranking to "feel" them working, seems like I could feel them work, but haven't verified via circuit test light (next test). All 8 injectors are new, so doubt any are bad, but ?? Pulled a few plugs, they were new @ same time injectors replaced (3 days ago!) & they are blackened as bad at the ones they replaced.
I'm really tired of this! :smash:

Buy one .Have you replaced the module? How many miles are on this car?

Starting problem - 1989 C4
 

The ECM is $85 for a re-manuf unit at Advance A/P so until I check with a test lite at the inj, I'm not spending the $85. The pressure tester was $20. not $50. & I intend to keep this vette for a while + my '96 Chev PU also as injection & might be needed for it one day.
My 87 vette only has 65K mi., my '96 PU, however has 132K & starts every time. :salute:

Not ecm, Module in distributor. Check if you have a weak spark by taking an old spark plug and pulling say number one plug wire, plug it in and lay it against the block. Start engine, you should have a nice blue spark. If it is yellow then chances are module is toast.

Starting problem - 1989 C4
 

I knew that...but it seemed most posts indicated ECM replacement solved their problems. Even that seemed as remote as ignition module going bad sitting in my garage for 2 months while I replaced the injectors. More likely is something I either didn't reconnect correctly, or dislodged during re-assembly. If it didn't run or didn't run well before the injector replacement, I'd think some elec part might be at fault...but just sitting with the batt disconnected doesn't seem logical for elec parts to suddenly fail. Of course, logic doesn't always enter into automotive problems. I'll check the spark tomorrow for intensity, thanks for suggesting it. I did notice that the fan comes on when key is turned on & while cranking the fan slows, indicating a draw on the juice. I'd better check for a bad ground. The fan shouldn't come on until motor has warmed up, don't you think?? I've also had to keep the batt charger on slow (2Amp) charge while all this testing is going on & one post said this was dangerous to the ECM. Could I have already damaged it??

Back in June of '03 The CorvetteKid wrote: "Hey blackvette89, the temp sensor that controls when the fan comes on and off is the one on the intake manifold on the front of the engine (just below the throttle body). It feeds the information to the ECM; it's the ECM that turns the fan on and off." Perhaps the ECM is turning on the fan at startup, (erroneously) drawing much needed amps from the injectors, preventing them from firing correctly. I do notice the fan slows somewhat during cranking, which shows there is a drawdown of voltage and/or amps. I'll try to unplug that sensor & see if it makes a difference, in addition to checking the spark & the ground connections. Bad grounds are one of the most common problems with all things elec.

FWIW....I've been fussing for months with slow-start, no-start issues when my '84 is hot. Changed wires, TB injectors, relays. Situtation got progressively worse. Pulled fuel sending unit to replace pump, found a small rupture in the one-inch long rubber hose connecting pump to line. Replaced the hose. Problem solved.

Starting problem - 1989 C4
 

Thanks Indianavette, but I think not relevant in my case. I've good fuel pressure (42lbs) at the rails. Drops a little when cranking to the 30's, & spark seems good. Haven't checked the individual injectors for firing with a test light yet. Intended to do that today, but was too busy. I'm still thinking I did something wrong when installing the new injectors.

While re-reading "ALDL" codes info I found this little gem:
"Clearing the Codes: To clear the codes from memory, remove the negative battery cable for a minimum of 10 seconds. Remember to remove the shorting device from the connector after you have read the codes. Disconnecting the battery will clear all stored codes and any stored memory (radio button presets, clock, trip odometer, average gas mileage memory, power seats). "Your ECM/PCM computer will also have to relearn timing/mixture/exhaust emissions."
So, I'm wondering how long is it going to take to "relearn" the timing/mixture/exhaust emissions??? Maybe that's why it won't start...after the battery was disconnected for 2 mos...it's not yet re-learned how to do it!!!! Anyone have any new ideas?? (The ignition wasn't on when I re-connected the batt, so harming the ECM/PCM wasn't a factor)

Mine stays disconnected for four months. Starts right up.

Starting problem - 1989 C4
 

Thanks, Tommy...
Then it's something I did or didn't do when replacing the injectors. I've rechecked all the fuel connections, no leaks. Checked all the vac connections, all seem to be correct. Still haven't had time to test-light the individual injector connectors. And I haven't located the ALDL plug, it's well hidden amongst what looks like a explosion in a spaghetti factory...in case it might lend me a clue. Spark is good & pump pressure at the Schrader on the fuel rail is 42 then down to mid 30's when cranking. It may have to wait 'til fall as I'm trying to get stuff done to leave FL for my summer home in AZ.

All the wires to the ALDL plug have been cut & all taped together in a big wad. Suppose this was done by ignorantjackass that installed the stereo or alarm sys or remote starter sys, or all three, so I've got to undo all that mess & try to figure out which wires go where! In re reading the troubleshooting guides, I see that #6) "Engine starts, but stops immediately" #3 is "Vacuum leak at gasket between intake manifold/plenum & throttle body." & since I had this apart to replace the injectors, seems like a good place for me to have left a leak. I'll check it out as soon as I can.

Vacuum leak? Car will for sure not run right. I always put a little tack adhesive and let it sit for a few hours on the gasket's so they have no chance of moving during reassembly.

Starting problem - 1989 C4
 

That's what I thought, might run lean, but it would run. I sprayed some WD-40 at the joint of plenum & risers, no diff. Still haven't had time to check inj's with a test lite, maybe this eve. after dinner.

The best way to clear the error codes in the ECM is to open the ECM power connector. This requires no tools and doesn't affect the other stuff:

http://www.misterpeachy.com/VettePic...6_Figure_4.gif

The connector only has to be open about 1 second to do this. This clears the error codes and the BLMs (Block Learn Multipliers). The BLMs will be reset to the default value of 120. Driving in a "normal" manner for about 15 minutes will allow the ECM to readjust the BLMs. The ECM uses them to calculate the fuel injector pulse width so your AFR will be off a little until they get tuned. The ECM must be in closed loop mode to adjust BLMs, so the engine needs to warm up first.

Starting Problem
 

Thanks, Cliff. Gives be something more to check out...that ECM harness connection to the pos batt might not have a good connection & I needed to check the ground connections as well. I'm sure it's something simple, just haven't found it yet. All the wires to the ALDL have been cut & bundled together & all taped with elec tape into a big wad under the dash...I guess it was some fools way to keep everything from hanging down when the remote start, alarm sys & stereo were installed, but it's a real mess to untangle & locate the "A & B" wires so I can check any codes. The A & B wire remnants still at the block appear to be a black w/thin white lines & a white w/thin black lines. Still haven't found them in the "Wad" yet, still looking. I'm 6' 230lbs & it's tight for me to get under the dash for any length of time.

Starting problems 1989 Corvette
 

Pecos, it runs! The fuel filter was definitly clogged. While replacing it I created another prroblem that I will have to attend to later. Thought I would be clever and drop the X cross memeber where it connects to the frame near the filter to give me more working room. This worked well but 3 of the captured nuts in the frame rail broke loose as I was re-attaching cross member so now only have one bolt holding it in at this location. Will have to use nut serts or something similar to fix this issue. Anyway after installing new filter and cranking over engine I still had no pressure at fuel rail ( have bought injector pressure gauge tool from Harbor Freight). I then pulled the pump relay and checked it out and it checked okay with voltmeter. I then hard wired pump at relay base and pump lit off and I now had 40# at the injector rail. I set up my meter today to test for pump relay signal from ECM with pump relay removed. Turned key to on and saw voltage at the relay base for a few seconds which meant I was getting a signal from the ECM. For the hell of it I turned key to start to see if I got a steady signal from the ECM during cranking and the damned thing started with out the pump relay installed. So I removed my testing equipment and installed the pump drive relay and car starts right up. The only thing strange at this time is the cooling fan comes on right away and cycles on and off. It used to only come on when engine temp reached 235 degrees. I don't know if I should be concerned about this now or not. Cleared all the stored codes and am going to drive it tomorrow to see if service engine soon light comes on again.