I have a 1986 IROC-Z Z28 305, automatic Camaro I picked up a 1988 PROM I made sure it was for the right transmission and engine, but when I popped it in the car turns over but wont get started. Is there something else I need to do to get it to run?

 

This is the one i picked up.

 

I did have the computer replaced, it is a remanufactured one from carquest. I don't know if that is the issue.

 

What is the 3 or 4 LETTER code on top of the PROM?

Moving to DFI & ECM.

RBob.

 

AKFS

 

That PROM has VATs enabled, injectors won't fire. If you want can get a VATs eliminator box to send that signal to the ECM.

RBob.

 

I thought this one didn't have vats... What are the versions I can use and which one is the best?

 

I have a 1988 Chevrolet Camaro IROCZ with 5.0 305 RPO LB9 TPI engine. I bought a Hypertech ThermoMaster performance PROM computer chip, A Hypertech 160 degree cool fan switch & an SLP 160 degree cooling thermostat. I ordered all of this from Summit Racing Equipment back in late 1989. My Camaro kept getting very hot and overheating so I called the tech guy at Summit and he suggested that I purchase these parts to correct the issue and I have not had a problem since I installed these parts. These modifications made my Camaro a completely different & much improved car!!!!!!! It doesn’t overheat any more and the improved performance & throttle response is TOTALLY AMAZING!!!!!!!! My gas mileage is even better.But Hypertech recommends only using 91 or higher gasoline octane because of the changes from mods but the gas mileage is much better than the stock setup. Since the automatic transmission is ECM & PROM chip controlled this shift points are more firm and smoother than with the stock setup. I would highly recommend & suggest this performance & mileage modification to anyone for their 3rd gen Camaro or Firebird. This was money well spent and worth every penny!!!!!!!!

 

HyperTech chips SUCK, 160 degree thermostats SUCK, and 160 degree fan switches SUCK!!!

Your car's 100% bone stock cooling system will cool your car just fine.

Did you live in Death Valley back in 1989?

When you say your IROC-Z was getting very hot and overheating do you mean the needle on the gauge was pointing at a number that scared me or that coolant was violently exploding all over the place under the hood?

 

Which is absolutely false. 170-180F is where a small block especially an iron headed ECM controlled unit likes to run. A 160F thermostat is not fully open until 180-185F. The 195F is not fully open until ~220F. Running 200+ is for making them into DOGS especially in hot weather. The Vortec 350 in my boat had a 140F thermostat in it as built. It ran cool and made power there. Much less detonation prone than the same engine in my Express van running 220+F when it was stock. I put a 160F in it and it absolutely ran far better. The ECM/PCMs pull a ton of timing advance and that absolutely kills power when the Coolant and IATs are excessively hot. The factory L31 350 in the Express would go nuclear in hot weather with the 195F thermostat. It would run hot because of 115F summer heat, pull timing, run even hotter, pull more timing, and then the clutch fan would fully lock in, it would add more load which made even more heat. It was a downward spiral until it lost solid 60+ ft/lbs of torque. Slapped a 160F in in it with a heavy duty clutch and it never ran over 182F. Was like driving it on a winter day after. No power loss and not excessive fan clutch engagement because the cooling system was able to get ahead of the hot running condition and the PCM was no longer adding more heat retarding the timing excessively to prevent detonation from overheating.

It was dyno proven even in the 80s that maximum power was made under 160F on the TPI 305s and 350s. I have seen the actual dyno testing of a TPI 305, torque vs coolant temp. It made 35 ft/lbs more at 147F than it did at 210F. Engine Masters did a whole episode on thermal testing.

 

I stick by HyperTech chips SUCK.

I stick by a 1 year old bone stock 1988 IROC-Z should run just fine with a 100% bone stock cooling system in proper operating condition. It won't be running too hot and overheating.

I did ask the guy if he lived in Death Valley in 1989 on the off chance he might actually have a use case for a HyperTech ThermoMaster chip, a 160 degree thermostat and a 160 degree fan switch.

Most of us don't drive our cars at maximum horsepower and torque all the time. Some of us drive our cars like a regular car. Some of us drive our cars in cool/cold weather and would like for it to warm up quick and keep our little fingers and toes nice and toasty when it's cool/cold weather outside.

You aren't going to get any of that in a 3rd gen with a 160 degree thermostat and fan switch. At 55 years old my little fingers and toes don't stay nice and toasty when it is cold like they used to when I was young. It's 67 outside and 70 in the house right now and I'm wearing socks to keep my little toes nice and warm.

This guy isn't driving a 7,000 pound A-Team van in the scorching hot 115 degree Texas summer heat pulling a grade uphill either.

If this guy was driving in extreme temperatures or just running his car down the track at Beech Bend go right ahead with the HyperTech ThermoMaster chip, 160 degree thermostat, and 160 degree fan switch.

 

Not if you live in the deep south. Its almost a must to run cooler fan switches on these cars down south in the summer months.

 

Your chip was controlling your shift points ? On a 700r4 ?

 

I stick by the stock cooling system needing help, especially here in Texas. They run too hot, performance suffers, durability suffers, power suffers, even AC cooling ceases.

The 160F thermostats I have had in GMs will still burn you out them. I have run 144F thermostats in several of my Nissan/Infiniti products and they still made decent heat.

I want maximum power whenever I want it. If you have never experienced power loss due to heat soak in 110-115F conditions maybe you should at some point. Remember I had a 91 Z/28 as well. It was a bone stock, low mileage car and I did the 160F thermostat, 160F switch and adjusted the tune in it to bring the ECM controlled fan on earlier.

My 2011 M56S would also actually go into limp mode because some bonehead at Nissan decided the cooling fans should only run 50-60% PWM at 0 mph and 99% at 25 mph to reduce fan noise. No those fans need to sing sitting in traffic in Texas heat. I installed a 144F thermostat, 19 psi radiator cap and enabled the fans to maximum PWM with both coolant and AC pressure at 0 mph. The car stopped going into limp mode and the ac was much colder after. F-cars are the same way especially dual fan units. The fans best both be turning early or you are going to struggle to cool the engine and the AC is going to struggle to cool the interior. Forget trying to keep a single fan car cool, they just don't work well.

 

There were 10 zillion of these cars back in the day, 100% stock. running at 220 degrees all day. Now all the sudden, GM is defective engineering. OK..

 

It is if you actually want the heads to stay intact and not crack. Also if you want to actually have any power and for your AC to be cold especially with a R134a conversion.

My stock 97 L31 350 ran so hot from the factory that it nuked the intake gaskets and grenaded at 57K miles from hydraulic lock on startup as a result.

I have actually run 143/144F rated thermostats in numerous vehicles as well. That was also the factory recomeended temperature for the L31 in my boat. Small blocks also all ran 180F thermostats for 2 decades before GM decided to crank up the temperature on them.

Also keep in mind with an Automatic, with coolant in the radiator at 220F, that is the minimum temp your transmission fluid will also be running. At 220F your transmission is cooking itself to death.

 

There were no mass recalls on motors back in the day. my car is stock, with 80,000 miles. and R12. LB9

 

Not hard to look and see what is happening even today with GM. It is laughible. They have engines locking up left and right due to faulty machine work and they slap a different oil viscosity in it and send it out the door. The L31s and several other engines like the 4.3L and 3100s in the 90s sharing the same style intake gaskets would grenade from a faulty intake gasket design and it was sorry about your luck, here is a quote for a new engine. No recall and zero owner assistance from GM. Same thing happened when 700r4s and 4L60Es died just after the powertrain warranty. Will not even get into the 80s stuff like the 4100 and Oldsmobile diesel failures. I personally would never own a new GM ever. If it is not an engine built by me in an older vehicle, forget it. I went to Nissan VQ/VK powered vehicles for all my daily drivers that rack up loads of miles ~15 years ago and I do not regret that decision at all.

If you do not see an issue with your cooling system I doubt you are in the deep south.

The TB coolant bypass alone on my TPI 305 was +6 whp and +8 wtq when I tested it. The TB and plenum both stayed much cooler. Cooled it down from 195F to 160F and gained another 7 whp and 15 wtq. Two very minor changes were worth 13 whp and 23 wtq. That power gain was everyday for months at a time anytime I put my foot down. If I own another TPI or LT1 it will immediately get a dual row radiator, LS1 dual fan assembly, a 160F thermostat, 160F fan switch, and TB coolant bypass.

 

I swapped a throttle body from a L98 to a LB9 because I broke the heads off a few screws trying to take off the IAC/coolant housing on the bottom to change the gasket.

I had to adjust the minimum idle air bypass and check the TPS voltage. I always do this at full operating temperature. It's amazing how much the TPS voltage will change from stone cold to full operating temperature. I leaned over the car into the engine bay and put my arm across the top of the throttle body and burnt the living Hell out of my arm. I instantly jumped 5 feet into the air. With the engine coolant flowing through the throttle body it gets hotter than a well digger's azz.

I don't know if I live in the Deep South in Franklin, KY but last summer it was 105 degrees and felt like 105% humidity because you could just see it in the air. Opening the door of my house to go outside onto my front porch just to check the mailbox took my breath away. Just that very short moment from being outside and back inside my glasses fogged over so bad I couldn't see out of them.

My Firebird ran and drove just fine without overheating and the AC felt good but not ice cold.

Late last fall I did my coolant, power steering fluid, and brake fluid flush and I swapped my 195 thermostat for a 180 and swapped the cooling fan switch to a 208/210 on and 198/200 off switch. My car runs cooler at more reasonable temperatures that I like to see compared to the factory stock configuration. Factory stock never overheated though.

 

I did something similar on my 87 G20 van recently. I was adjusting the temperature of the Flexalite fan controller. Accidentally rested my arm on the top of the Cold Case aluminum radiator with the engine running about 185-190F. Needless to say I paid real close attention to where my arm was in relation to the radiator after.

This was after a 1 hour long idle heat soak with the hood closed the other day in 90F ambients. I test idle heat soak on anything I build/modify because these major Texas highways and interstates in the larger cities can become complete and total parking lots. I would rather find out sitting at the shop that I have an overheating issue rather than in a traffic jam on a very hot day. I cannot even begin to explain how many times I have been in traffic for over 2 hours to move 3-5 miles. Numerous times wrecks have shut down the whole highway and you put the shifter in Park and just sit for 30+ minutes. It did extremely well with a 180F thermostat, the Cold Case radiator, a 12" Tahoe condenser pusher fan and a Flexalite 4600 fan kit on it.


Since I am going to be towing heavy a lot this summer with my 97 that has the 383 in it, I just did a big cooling system uprade on it. It will also have a 143F Robert Shaw style thermostat in it, atleast for the summer. It has dragging an 8K enclosed trailer across Texas hill country multiple times to deal with moving the house and my shop from North to South Texas. The backroad highways I will be on are very nice and 75 mph posted. Both the 383 and 4L85E are going to be working hard and keeping it cool is a huge priority. I will be dragging a 24' x 8.5' wide tandem axle trailer loaded up to about 8K on each trip.