Need computer help

J

jdevs1

Member
#1
#1
I have an 89 GT Conv with auto tranny. Car was running like crap,the previous owner had put long tube headers but never installed o2 sensors. I brought it a mechanic who installed the o2 sensors and tried to run a diagnostic check. He said he was not able to access computer and after checking harness said it appeared computer was shot. He then replaced EEC with reman one. Still had same problem. Car runs a little better with the 02's but still runs rough for first couple of minutes. Computer seems to be doing something ,engine stumbled when maf unplugged. After letting him try to figure it out for a couple of weeks I took car home and now trying to figure out what to do next. Anybody
ever use one of those cheap scanners from auto zone? Is it worth buying one? Anybody ever have anything similar with their car? Any help would be appreciated.
 
cobra20sc

cobra20sc

Well-Known Member
#2
#2
wow, where to even start.

i would start with a simple tune up:
* new plugs, wires, cap and rotor
* check timing 10 deg BTDC with the distributor spout disconnected
* check all hoses, check for any leaks, (while engine is running)
* check fuel pressure
* do compression test

You don't need a code reader to pull the codes. There is a connector you can jumper to get the MIL light to flash the codes
Did you say it has a MAF? Thought they came around 1990 unless that was converted or was an early on version.

Could use so more description of the symptoms. How many miles on it?
 
TheWhiteFox

TheWhiteFox

Member
#3
#3
when you say rough is it a misfire or when you are on the gas it stumbles?? is this at idle?? etc. MAF came on board in 88 in california, 89 in all 50 states, does it have msd box, different distributor? these would all help with where to start
 
J

jdevs1

Member
#4
#4
It's all stock except for cold air,pullies,&exhaust. It's the problem with getting codes out of computer that confused me. It's also running rich. I cleaned IAC and coolant temp sensor replaced, timing checked.
 
teknik

teknik

Well-Known Member
#6
#6
If the guys scanner won't read the computer, First thing to do is to
disconnect the computer harness and look for any pins that were bent or
pushed out so they are not making contact. Do the same for any other
major harness connections. Then check the fuel inertia switch. It is
not unlikely it is tripped halfway. Smack it so it trips fully and hit the reset
switch.

These might sound like fat chance in hell solutions, But I have seen
this happen to at least a dozen cars in my travels. Plus , doing these
checks first, does not cost anything, and gives peace of mind that
all your bases are proper. And never overlook vacuum hoses !!!
Especially, if Long tubes are on there and the EGR system
most likely touched.
 
J

jdevs1

Member
#9
#9
Thanks GoEasy for the website, looks like theres alot of useful stuff on it. Hooked up test light today to pull codes. In KOEO mode I was getting code 67( neutral safety switch) I don't see how this would cause engine to run badlly, but I tried starting car while in gear and sensor seems to be working fine. Then tried testing with engine running and test light did not light up at all, should have given code 11 if all sensors were functioning. I already cleaned MAF and IAC, going to try to track down multi-meter to test TPS. Vacum lines looked good but going to replace a few that look questionable. Tried inertia switch trick, no luck. Any other suggestions would be appreciated Thanks
 
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