Recently bought an '88 IROC-Z. Dealer changed the engine from a 305TPI to a 350TPI...seems they screwed up the 305 by getting trash in the oilpan when they changed the pan gasket.

Any rate, they kept everything from the 305 and replaced on the 350. The car has failed Texas state emissions test 4 times. An old and wise parts guy at a chevy house said 'change the chip'. I ordered a 350 IROC chip and just replaced it.

The chip that I took out is an Hypertech model. 128842

I went to their website and tracked down the part number and here's the info on it:


128842 THERMO MASTER (COOL FAN SWITCH RECOMMENDED IF EQUIPPED WITH ELECTRIC FANS)

It is obviously an aftermarket chip. Question here (FINALLY), is there anything else that needs done if you replace a chip?? Or does it just make itself at home and take over duties? The car started up fine and I think I noticed less performance out of it. Which I guess is to be expected.

ALso could the aftermarket chip on the wrong size engine have been contributing to my emissions problems? Need to run out half a tank of gas to get rid of Emissions Pass chemical. Then I can try it for the 5th time.

TIA

 

I replied to one of the your emails on the other boards.......Did they replace the 19lb injectors with the 22lb injectors when they installed the 350? The 350 engines comes stock with 22lb injectors.

You'll need the correct injectors to work with your new prom because if it is a 350 Prom it is programmed for 22 lb injectors.

 

Yes, you did reply and thanks for that one and this one. No, they/we have not changed the injectors as yet. At $60 (O'Reilly's auto parts price) apiece X 8 I am probably going to have an issue with them and it will fall back on me.

They were real good about getting the colling problem resolved (ultimately took the new 3 core radiator). Course they gave me a one year warranty on the new engine so they had a definite interest in getting the cooling resolved.

Back to one of my questions, could the 305 aftermarket chip be so far off that it was throwing the emissions out?

Also does anyone have any info on Hypertech. Their chips any good, anything special????

 

the hypetech chip that I have personally read and seen is from an 89 305 TPI 5-speed car. The only changes to the chip were as shown and lower fan on/off temps, that's it. The comparisson is to an APYS file for a similar configuration. The chip isn't radically different from a stock chip.

 

Thanks.................

 

I had one of those chips before and at they don't change much of anything. I'd becareful running the 350 chip with 305 injectors because it will make you car run lean. It will also probably make it run like crap because the computer is making adjustments thinking the injectors are bigger.

Get the 22lb injectors and troubleshoot from there.

Call rich at Cruzin Performance and see if he can hook you up with some injectors for a reasonable price.

http://www.cruzinperformance.com/

60$ X 8 is way too high. You should be able to find them a lot cheaper.

Later

 

ya if all else fails get some 24lb for $230 from jegs or summit and get a custom chip burnt for them. about the same price.

 

I have 19lb/hr injectors on my 355 and it runs perfectly fine. No lean conditions anywhere, and it's actually real easy to make it run pig rich.
Instead of buying injectors, invest in the prom burning equipment and change the injector constant. Once you learn what's going on you'll be able to tune it perfectly then which is an added bonus..

 

Recently bought an '88 IROC-Z. Dealer changed the engine from a 305TPI to a 350TPI...seems they screwed up the

Forget about this. The fact that the car is MAF and you are talking about an emissions test makes the 305 350 part of this irrelevant. The WOT issues will need to be addressed but closed loop operation with a 19lb PROM and 19 LB injectors and MAF means for the most part that the computer uses the MAF to "sense" the amount of air and the computer determines the amount fuel to inject. AS the displacement goes up the amount of air "measured" goes up also as does the fuel.

An old and wise parts guy at a chevy house said 'change the chip'.

By changing the chip you are leaning the engine some 15% (uncorrected) by lying about injector size.

The car has failed Texas state emissions test 4 times.

Start here. They should have given you something that said what did not pass.

For high oxides of nitrogen look at spark timing compression(carbon build up maybe), and egr operation.

For high HC AND low CO the car is lean. Fix vacuum leaks etc. Get the car scanned to find out what the BLM numbers are. The chip will be a problem if the BLM is stuck at 160. Make sure you have taken care of all intake tract leaks before blaming the chip.

For low hc and high CO the car is rich check cold start injector and fuel pressure and trouble codes. Get car scanned to get BLMs.

Use the 19 lb chip with the 19 lb injectors until you get 22 lb injectors then use the 22 lb chip. Stay out of WOT until you getall this straightened out. Your motor will thank you.

HTH

John

 

Last test it failed HC and CO at both 15mph and 25mph. Time before that it only failed CO at 15mph. Between tests, I put a bottle of Emissions Pass (guaranteed to pass, etc, etc, yadayada) and it had not run out completely. Still had half a tank when I topped off the tank. Am emptying the tank before filling it tomorrow morning and getting a retest.

If it fails, taking it to a garage that has equipment to test all 4 gases. Same place that inspected it last two times.

 

Just an update....


Had new catalytic converter installed...Flowmaster HighFlo and ordered and installed 21lb injectors from Summit..(this was at the advice of Rich at Cruzin Performance). Took it up this morning at he D#&^ thing passed.


Thanks for everyone's help and recommendations.....

 

Congratulations & glad everything worked out. Isn't Rich cool to deal with at Cruzin Performance.

Later