LAGATTU

Hi everybody ,
I have one 93 Corvette ,150,000 miles facing engine stops . Codes defauts ,H 16 ..............that 's all .So far I have changed recently ,fuel filter, fuel valves ,sparks wires ,IMC ,coil , opti Petris ventilated .During filling up cooling water procedures ,the motor sarts ok a lot .So after some cooling leaks repairs ;Start motor again ,ok , ,up to cooling fan starting .And after ,about 20 minutes,iddle speed ,was erratic ,instead of 500 ,going down to 400 ,and then back to normal ,and after a while engine stop .Since opti renew

LAGATTU

I continue ,engine have ran 25 minutes...........and now at opti outlet no sparks ............Is anybody have advices ,what ,I have to do now ,,I am in very stress,with all money I spend ,with no results .L

FAUEE

Search for shbox's lt1 no start guide. My cars had vats issues, causing it to not enable the injectors. Had to get it tuned out.

Kevova

opti sends signal to ecm. Ecm sendes signal ignition module and injectors. Will injectors pulse or noid light blink. 93 uses batch fire or pulses 2 groups of 4 injectors so you need to check several. If the injectors blink ecm is getting signal from opti. If not, problem is opti, wiring, or ecm. Codes? Have you checked for spark at coil? Do you have service information? I think you will need a DVOM and a trouble chart to figure it out.

FAUEE

If it was the opti he would have a code from the lack of low resolution signal.

Kevova

Gotta ask the question. Opti sends 2 signals If one is there and the other is not code sets. If opti sends no signal may not set a code. Happened to me.

LAGATTU

Hi all ,
Thanks for your quick replies ,I appreciate .So situation now ,about vats ,I don't care ,because ,somebody installed a special device to cancel it .So far I have only checked sparks out of opti ,through ,the only cylinder ,I can reach with opti .,Not yet test sparks at coil outlet ,will do soon;about codes before I crank ,for 20 minutes ,I had not any codes ,only C 12;After all cranking tests,I got H 16 ,H 41 .So I erase all codes ,and again berfore cranking again ,no codes ;Cranking not succesful ,checking ,codes , C 12 ,H 16 ,that's all .
About injectors ,I run with ,for only 400 miles .What I am thinkling maybe I damage new opti ,with water leaks ? they were very tiny. ( if some water have been inside ,do you think ,if to put some electric radiator..,will dry the system..)....This aftertrnoon ,I will go on..and giving you news

Kevova

You need to diagnose the h16 code again since it still occurring.

FAUEE

H16 is the low resolution not seen code. Your issue is either Opti, PCM, or wigin.


http://shbox.com/1/4th_gen_tech2.html#opti_test

LAGATTU

Thanks for your informations ;I just check now ,no firte at coil end .......Before erasing codes ,this afernoon ,I had ,H 41 ;,H 16 ,H 72 .after erasing , C 12, H 16 .Whjen after 20 minutes engine stos ,,I try to press on throttle ;and rpm increase was very weak .....That's remember ,when engine stops on the road,rpm was erraetic ,and after no possibity to crank .........I had experiences with opti failure ,so I read on, threads ,that if you replace your opti ,engine crank immediatelyu ,and it's impossible to do wrong things ,so I have done the job ,and when finished ,,I made cranking tests ,without water pump,no success.........After a while ,I erase codes ,and checking coil fire ,ok ,then on opti ,ok .I made a lot of tests ,and put back water pump .Engine crank ok ,many times ,until these famous 20 minutes .
After thinking to all of this ,finally now ,I got the same symptoms ,when first time I had problems ,on roads .Previous opti was 1,500 miles old .......so maybe ,it was not necessary to replace ,and former problem ,is still there.........
Friends tel me that maybe ,my ECM , needs overhauling......maybe for your information ,is usefull ,just before all that ,my automatic box ,rebuild ,throttle cable replace,and TV cable setting ....that's all .........

FAUEE

I'd lean towards ecm or wiring. Unfortunately, those are hard to test, you have to find that you have signal at the opti, but not the ecm plug.

LAGATTU

Hi all,,
Aftert longer analysis , ,before opti changed ,engine idle speed ,was going ,up and down once ,and was not possible to increase so much rpm ,as I was not far from home ,I succeed,to go back ,As I had low fuel in tank ,I was thinking fuel lack ,I fill up with 3. gallons,and the day after ,I crank ok ,and rpm ok .I drive 3 miles ,and suddenly ,power loss ,and stop engine at middle road ......At this moment ,not any more cranking ........Back home ,change opti , with Petris ventilated ,no cranking,Codes erasing ,then coil fired ,opti to plug fired ,and engine starts many time ;water pump ,back ,,cranking ok .Engine tests , stops after 20 minutes,and since no more firing .It seems to me ,that is the same problem ,that before opti changement (and maybe it was not necessary to change opti ....... ) .
I am quite lost for researchs ,because with Service manual ,thers is not special page for that .Could give me some directions for looking after ,thanks ,in advance.

Kevova

There is a chart in section 6E of manual for no start. When car quits that is when you need to test things. Unfortunately ECM is hard to find to substitute. ECM is 92-93 corvette and f body lt1 only. If you carry your manual and " no start kit" in car you can diagnose from side of the road if necessary. No start kit consists of fuel pressure gauge, spark tester , noid light, and DVOM. A couple jumper wires 24 inches long could be handy also.

gdgeorge

Everything except the 12 is a history code. Clear them and see if they reset. If you've done that, changed out the Opti, and the car is still setting a code 16, you might check the wiring from the PCM to the Opti. It should show voltage at the plug into the Opti. I don't have my FSM here, but if this is wire I think it is, pull the cover off the passenger side injectors and you'll see that it runs along and to a plug attached to the block. It's a great place for rodents to infiltrate and chew the insulation/wire. If the wire is bare, it can short out on the block, thus causing unhappiness, especially at speed, on an eight-lane highway.

Best,
Jerry

LAGATTU

Thanks ,I will go ahead with your advices ......

LAGATTU

Hi guys ,
I am still ,no firing ,and I have seen on forums ,that ,due to code 41 ,to check CKT 800 TAN ,I don't found the meaning and precise location with service manual....Another thing ,as after my opti renewal ,I have succeeded to fire about 10 times (no codes left ),my engine stopped ,after 20 minutes ,( just before stop ,iddle was not steady ) ,now with code 41 ,what could be my problems .? I start to be fed up........