Hi guys (and girls)


I have been putting my 89 Iroc together for the last 4 years and now I have a problem. Its a 383 tpi stroker with extensive mods...GM Ramjet intake with vortec heads...30 lbs injectors...fuel pressure regulator (running around 45 psi) custom burnt chip..with all the info burnt on it (except I am still running stock maf) and told LS Racing I was putting a after maket one in..all new Elderbrock rails...1.6 rockers...
The original computer was for a 305...does this create my probem??tried the old chip but still have the same problem
The motor start fine but as soon it is hot it stalls and do not start...timing is set a 0 degrees...after about 20 minutes I can start it again and have about 20 minutes running time....talk to a couple of mechanics and no answer but to change computer....does anybody know where I can get the computer numbers to make sure I have the original since when I check there was writting on the casing of the one in the car( S10 2.5)...was that compatible with my car....thanks

gilles

 

You'll have better luck posting in the correct forum..

I would try either General Tech/Engine or the TPI forums.
They should have some advice/suggestions for you there

 

sounds like the ignition module in the distributor, they quit when hot when they're bad and will work again when cooled down.
but that is just a guess, you need to check what is missing when it doesn't run. spark, fuel or air. no spark-bad module, no fuel-bad fuel pump, no air-bad valves, compression, ect.

 

oh ya....thank you...was frustrated and was not using my head again....will go post there....thanks for the advice...


but since I am here....did more troubleshooting today...no pulse at the injectors when hot...tried another computer and chip..same result...check all grounds at puter and relays but nothing ...tried another ignition module too today but same result....will troubleshoot more tonight and hope to get better result...thanks for the info and I appreciate any help

gilles

 

You may be running to much advance on your timing try backing it down.

 

I'd say your problem probably has something to do with the M.A.F. sensor that you had the chip burnt to use not being on the vehicle. Your old computer won't fix the problem either because it's for a different motor too. Get the M.A.F. sensor on there that's supposed to be on there and try it. If that doesn't help, then you might want to make sure that the fuel pressure is right when the car's running. If all that fails, you should really start looking into the emission control systems.

 

you could DISCONNECT the MAF and it still should start and run, maybe bad, but it will start and run. so I would say it's NOT the MAF sensor.

no injector pulse indicates an ECM or module problem, but since you have changed both those, I am stumped as to what could be the prob.

wait a minute,

could be the pick up coil inside the distributor not signaling the module.
grab the green and white wires and lightly tug on them to see if they're broken inside the insulation or pull off. also check that the connections are clean.
if you have a multi meter, connect it to the green and white wire ( with it unplugged from the module), have someone crank the motor and see if there is AC voltage while cranking. (you should check it when it's hot and having the problem, not when cold and it runs)

IF not, replace the pickup coil (remove distributor, pin from drive gear, drive gear (note the position), shaft, clip holding on the pickup, reverse for assembly.
you might have to spray the shaft with some penetrating oil to get it out of the housing due to oil deposits on the shaft. Just be patient and persistent, eventually it will come out.

if THAT'S not it, I am at the end of my suggestions, and might suggest there is a wiring problem.

 

I'm sticking with the M.A.F. suggestion. The E.C.M. sepends on the M.A.F. for air specific readings. If it's expecting a bigger M.A.F. to be giving it the readings and you've got a smaller one on there, I'd think that might be enough to confuse the E.C.M. with the newly burned chip. Of course it could be dirty or rotted wiring or connections to the Distributor or the E.C.M. too.

 

MAF has NOTHING to do with spark production. wether it's hot OR cold. if he is losing spark when it's hot, it's NOT the MAF.
the MAF measures the amount of air coming in the engine, and is not related to spark.

IF, in fact, he is losing spark like he says when it's hot.

I ran the stock MAF on my 406, and it turned 12.20's with street tires and a 3" flowmaster.

if changing his MAF fixes it, then I need to close my shop and go work at McDonlads.

 

You're forgetting about the E.C.M. chip I think. Fuel tables are based on it. They get their readings from the M.A.F. sensor. This could be a symptom of the problem. I listed rotted, dirty wiring to the Distributor and/or the E.C.M. as well. I probably shouldn't make my posts so short, but I thought people would read the whole thread.

 

[QUOTE]Originally posted by iroczracer07
Of course it could be dirty or rotted wiring or connections to the Distributor or the E.C.M. too.

In case anybody missed it.

 

yes, I read the whole post. and yes it could be a connection at the distributor or ecm, you are right.

what I am saying is that if he is losing spark when it gets hot, it has absolutely NOTHING to do with the MAF, spark production and airflow are NOT related.

 

And a stock T.P.I. M.A.F. sensor used with a Ramjet intake wouldn't be wired any differently? Maybe you know the answer to this, but I've never had the pleasure to play around with a Ramjet manifold. So, as far as I'm concerned the M.A.F. sensor is still something that should be checked out.

 

3 wires:
1.)ground
2.)5 volt supply
3.)varying sensor voltage sent back to the computer.

same as any aftermarket MAF.

don't care what kind of intake it is.

Iroczracer07: what KIND of auto experience do YOU have?
are you a tech?
or do you just drive?

 

I've got plenty of experience on regular F-body's, but I've never seen a Ramjet in anything other than the G.M. Performance Parts catalog. They come with a manual that I've never had the pleasure of reading. My main concern is that the M.A.F. is a variable, since the original poster never verified that he did or didn't have spark. If he did and I missed it, I apologize. I'm not saying you're wrong, just that we don't know enough to rule out the M.A.F. and/or bad connections. Sometimes it's the simplest things that bring everything crashing down. Since you posted the wiring Set up for the M.A.F. as the same as every other M.A.F., I take it that you have seen and worked on a Ramjet set up before. Now, if the original poster could verify whether or not the wiring is fine and if he has spark when it cuts out, we can get back to the business of trying to help him out. I recognized your question about my experience for the attempt to call me into question it was, but I'm not going to rise to the bait. I'm on here to help people out just like everbody else. Intakes shouldn't be generalized. Not all M.A.F. sensors are the same size and not all F.I. systems work exactly the same. Case in point, batch-fire and sequential firing of the injectors. When dealing with something I've never worked on, I like to err on the side of caution. It usually works out better for me that way.

 

Hi guys,

Sorry for not getting back on this subject...It was the ignition module...it was brand new distributor and I though I was safe there but I went to an Accel one and cure the problem.....but I am running rich and should invest a an aftermarket maf to correct this....do you think a later model maf would do the trick or should I spend the big bucks and buy a Granatelli adjustable one...very expensive and would prefer to buy one form an newer car..Lt1 or such....from ebay.

Lots of time now since I went for my first ride and now have antifreeze coming out of my exhaust%$#^

this after a 4 year building stint and over $8000 (Cnd) in motor....I am hoping it is the intake gasket and not a header one since I took off the intake for modification and found out after that when you put in a GM Vortec intake you have to use special intake bolts and I did not....if not its a trip to the speed shop and argue with them since there is no warranty on their Hi-performance builds...only have about 35 miles on engine......what a crapper!!!!!! lol

again thanks and very interesting debate...enjoyed it and learned form it..

gilles

 

I thought you had a specific one in mind. Oh well, as long as it's the right size to match the computer chip, it shouldn't matter too much. Just got to get the air/fuel mixture right. As for the anti-freeze in the exhaust, you are using Vortec heads and a specific Vortec style intake, right? If you are, double check everything to make sure you have good seal on the intake and heads. If you had any kind of porting work done, check to make sure a water jacket wasn't hit by accident. Please excuse our debate. As you can see, Gregbruce was right. My hat's off to him. I also said it could be in that area, but I troubleshoot differently than he does. I don't like variables and am therefore want everything as it should be first. To my credit, if the M.A.F. sensor was already on there, you wouldn't have asked about it. To his credit, going after the Ignition Module had it running faster. Hope you get your ride fixed soon. Let us know where you're at.

 

Hi Iroczracer07,

Hey thanks for the info....I found my leak..it was the intake gasket....if it is from gm it uses special bolts and is a very low torque gasket (11 ft/lbs). I did not use those bolts and overtorque the ones I had (20 lbs) You guys really seem to know your stuff and is really helpfull to us lower knowledge guys lol. Anyway do you think my computer in my 89 would recognize a newer maf sensor...I am really running rich due to the 30 lbs injectors and would like to give more air in...I am thinking of bidding on some ported maf on ebay but I cannot see the connector, do they have the same amout of pins as my 89....the ad says it is form 96 and later models. I took the screen off mine to try and improve it and notice the middle of the maf is not the same as the one on ebay.

My car is really running great beside that and enjoy the 460 hp (shop estimate) its putting out. Frigging gas (super) is hard on the ole wallet though.

thanks

 

I thought you had already gotten a custom prom chip. If you don't have one you might want to get one. Ask around on the computer prom and programming board and I'm sure someone will point out a good tuner to have burn your chip. It'll help out with gas mileage, power and the new M.A.F. sensor you want.

 

Oh ya, I have a custom prom chip from LS Racing done but I told him that I was gonna have a aftermarket maf in the car but never got one yet so there might be a little conflict there in the chip. Also I am running around 43 psi...when I took my intake off to change my gasket I notice there was a fair amount of gas right on top of the pistons... mayby I will try to set my psi down a bit and see how that goes.

 

You have the stock maf and the adjustable one. There are no other MAF's available for our cars. From other post the adjustable one is crap, so I would basically stay with the stock one. Thats the one I am using in my 383 with a Chip from LS Racing.