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GM 502 ram jet, tec gt problems.

9K views 15 replies 4 participants last post by  ogre 
#1 ·
Hallo everyone.
Im calling for help in little Denmark.
We have a 56 bel air, with a 502 ram jet, and a tec gt, from electromotive.
We got problems with cold start, but when it finally starts, it starts every time.

So we where wondering if one of you guys might, would sent us screenshots, of your setups. So we can check if we got something wrong, on ours.

Thanks
 
#3 ·
Theres a Electric fuel pump, making 45 psi before start. Its a aeromotive.

The ignition is working just fine, and its running really good, when its started.

The ilde air control is the orignale, which came with the ram jet. If its that your refering to?.
 
#6 · (Edited)
lets check a few things..

since i am half a planet away.. its hard to come over..

lets check the power to the ignition system.. with a test light.. i am expecting you have a HEI ignition system.. probably a remote coil small cap type.. the power to the coil.. the pink or red wire.. probe it while somebody slowly turns the key from OFF to ON, to Cranking.. back to ON.. then slowly OFF..

there is an issue with ignition switches used with GM points cars.. the IGN1 circuit opens when the key is in the cranking position .. this is because while cranking the ignition power comes from the R terminal on the starter solenoid..

with electronic ignition.. you will want the results to be bright. bright bright..

if you still had a point type ignition it would be medium, bright, medium. as the resistor is bypassed in the cranking position.


do you have some kind of scan tool... that will display live data stream to allow you to see what the engine controls are doing..

with conventional GM fuel injection.. i like to see TPS voltage below 0.98 volts.. usually someplace between 0.35 and 0.75 volts.

i would like to see with the engine warmed up.. coolant temp over 190F/85C the IDLE AIR COUNTS (IAC) between 20 and 70 at hot idle in park. this gives the computer the ability to back the idle air control motor out to about 120 counts for a cold start.. so it will fast idle.

i know you mentioned that you have fuel pressure.. but can you do the voltage test ON, Cranking, ON.. at the fuel pump power circuit.. so you make sure that when you turn the key on.. even before the engine is cranked.. the PCM has commanded the fuel pump relay to turn on for at least 2 seconds and less than 3 usually.. to build fuel pressure prior to cranking.

i will have to dig up the installation instructions for the Ramjet 502.. see how they handle this.

i was looking around for my image of the later GM in dash ignition switch that usually gets used with electronic ignition conversions.. it did not open the ign1 contacts while cranking.. it does have a pair of terminals G1 and G2 that could be used with an additional relay.. to power up the fuel pump relay while cranking. but the PCM should handle that just fine as long as the system does not loose current.

you may also want to monitor the power to the PCM.. during another Off, On, cranking, On, then off tests..


edit... i am taking the engine came with the installation and service manual..

https://chevroletperformanceparts.com/p/service-manual-ram-jet-502-2

i see your post that if you touch the throttle it will never start.. touching the throttle will usually cause the engine to flood.. only holding the throttle more than half way open without pumping will clear the flood and turn off the injectors to allow it to start..

fuel injected motors don't need to touch the throttle to get them to start.. if the idle speed and Throttle position sensor / idle air control are within specs..

this is a marine version and probably slightly different than what you have.. but the fuel injection system will have the same diagnosics..

http://www.pirate4x4.com/tech/billavista/MEFI/MEFI 4 & 4B DIAGNOSTIC MANUAL (L510005P).pdf

looks like the TPS voltage should be exactly 0.60 volts with the throttle closed..
 
#7 ·
Sounds like A/F problem.
Prolly need to go back to B2 in the instruction manual The SE0 and SE1 parameters seem to be in play here.


Looks like a GM IAC on the throttle body.
I skimmed the article in the instructions. Seems the factory components need a slightly different value /adjustment than the proprietary components.
 
#8 ·
The ignition is tec gt's system dfu coil.(electromotive)
And it works fine.

We have a pc, so we can adjust everything on the car, with the tec gt system. We have adjusted the one sec. Starting enrichment, but cant get it right.

I'll try to check the ilde air tomorrow.

The fuel pump activates for 8 sec. Before start, so we have the 45 psi.
 
#9 ·
Wayne, e is using electromotive electronics.It come with softare to interface with his Laptop


I doubt the PID values are exactly Like factory GM but are probably similar...close


The system has definitive instructions for setting cold start enrichement.
seems it has at least 2 compensatory operations for cold start comingled with base settings.
I am thinking that is what is ailing it.
My guess is to lean at startup


Total Engine Control TEC GT - Electromotive Engine Controls


look at TEC GT instructions
 
#11 ·
i would start by backing out the IAC more for fast idle speed without going too fast so you don't overspeed the engine as the oil pressure builds..

air bypass is probably easier to adjust than fuel..

i have not played with this TEC fuel injection system and how its programmed..

while doing this.. cold start set up... you might want to protect your engine by adding a remote starter button so you can crank the engine with the key and computer off to bring up the oil pressure just prior to your cold start attempt.. no use dry starting the engine.. just an idea..
 
#15 ·
After checking , I see you are right Ogre.The tec gt doesn't use one.
No MAF on this one (speed density)
It has an IAT , used in the intake manifold (MAT or manifold Air Temp)
A lot of air flow density systems have the IAT incorporated with the MAF
 
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