When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a 86 305 TPI that overall runs decent. I have a few questions though as I want to be as close to like new as possible. 28,000 original miles. Car starts good cold but will take a few more cranks hot and sometime a crack of the throttle when hot. At stop signs the idle speed in gear hunts a bit 400-600 rpm.
Then the odd one today. First time I ran the AC down the highway and the service engine soon light came on. I stopped and turned off engine and restarted and light went off. Down the road about 10 minutes with AC and light comes back on. Drove all the way home without AC and no light. Ideas what is causing that and thoughts on other questions above?
Not sure I can get a code, When I stop and restart it the light is off again. Will the code be stored even if the light goes off? I thought about going to Autozone to have them pull a code but wasnt sure it would pull a code if it goes off.
I use a bent paper clip to jumper the pins, works just fine.
The SES light itself will flash to give you the code. For example, a code 36 would be 3 flashes, pause, 6 flashes. Then that will repeat 3 times, then go to the next code. The ecu always starts out by flashing code 12, which is telling you that it is working. Trouble codes follow the code 12.
Welcome to the world of OBD1.
I drove it this weekend with AC on the highway. Took a while but service engine light came on. Stopped and jumped the leads. Turned Ign to On and no codes. Code is not staying saved when turning off the Ign. Can I jump while its running to get the code?
If you try to get the codes engine running you enter into field service mode. You might have a bad ecm .
+1
I remember one of the Firebirds I used to own would always throw a code 24 (VSS) but the problem is that it would not stay in the ECM memory & would only set when the car was moving. Figured out it was a code 24 by parking on a long steep hill then turning the key to RUN and letting the car roll down the hill while the ALDL was 'jumped'. ( good times ! ) I'm not exactly sure what was responsible for it because I replaced the ECM, speedo, VSS Buffer at the same time and the problem disappeared.
Sounds like leaky injectors and or leaky fpr diaphragm with a faulty tps sensor. Check for fuel pressure leak down after shut down for injectors. Even with low miles the old Multecs are probly done, gas with ethanol is known to kill them. The voltage at tps should be .54, I had a similar issue when I got my car and changing those things helped a lot, also if your car has cold start injector those can be prone to leaking as well so look into the delete kit from Hawks. South Bay could set you up with some Bosch 3s and fpr.
Last edited by Reddragon88gta; Jun 4, 2019 at 09:12 PM.
Those look like original injectors. Have you had the fuel pressure checked after shutdown to see if they’re leaking? Also sometimes it’s best to have a pro look at it to pin point the problem and then you can fix it, that is as long as you have a good mechanic. Ive done that a few times rather than throw money at it and hope it fixes it.
Last edited by Reddragon88gta; Jun 11, 2019 at 07:22 AM.
my thoughts is that if it is taking a bit to crank, then youre dealing with a fuel issue. clearly the cold start injector is fine, but if the rest are giving a pain, maybe the fuel filter is clogged? I know this is probably way off the trail of suggestions, but I know my car takes a while cranking over when hot or cold because my fuel pump doesnt have a check valve inside so it drains back (used a racetronix pump). however when the car is running its fine. I'm wondering if maybe youre not getting enough fuel to the rail? IDK. i'm prob way off
did you try checking the resistance on the injectors while they are cold and hot?
What should it be? When I turn the switch to on I dont hear the fuel pump run. I only hear the fuel pump while the car is actually running. Shouldnt the fuel pump kick on when you turn the key to on position even without starting it?
What should it be? When I turn the switch to on I dont hear the fuel pump run. I only hear the fuel pump while the car is actually running. Shouldnt the fuel pump kick on when you turn the key to on position even without starting it?
Fuel pump should cycle for 3 seconds or so at initial key on. If it doesn't, then you are going to see long crank times..... (pump won't run till oil pressure comes up.)
Even with low miles the old Multecs are probly done, gas with ethanol is known to kill them.
They didn't go to Multec injectors until 1989. 1986 would still have pintle style injectors from Bosch or Lucas, aka the 'good' injectors. It's a moot point anyway, since at this point any stock injector is due to be serviced anyway, and it's easier to just replace them.
Originally Posted by Dragster Racer
Can anyone tell me by looking at these injectors if they are the stock originals?
Is this the cold start injector that can be deleted? If you delete it does ECU need to be programmed? What are the negatives of deleting it?
No way to tell that they're 100% original to the car, but they're the right style, right color, etc. Chances are they're original equipment.
No Sir, that there is the oil pressure sending unit. The cold start injector is between the runners in the middle of the intake, not at the rear. It's hard to miss, it's got a square plug just like the rest of the injectors, and a hard tube going into the top of the injector to supply fuel from the fuel rail. Chances are very good that the CSI is not the problem.
When you checked the codes did you at least get code 12 three times? If you didn't get code 12, you're doing it wrong, or the ECM is shot. Code 12 tells you that you're in service mode, and that the computer is responding as it should.
Fix the obvious problem (the code) first, and deal with the rest later. Following a code is easy. Trying to diagnose a half dozen symptoms as one issue is a bit of a chore.
They didn't go to Multec injectors until 1989. 1986 would still have pintle style injectors from Bosch or Lucas, aka the 'good' injectors. It's a moot point anyway, since at this point any stock injector is due to be serviced anyway, and it's easier to just replace them.
No way to tell that they're 100% original to the car, but they're the right style, right color, etc. Chances are they're original equipment.
No Sir, that there is the oil pressure sending unit. The cold start injector is between the runners in the middle of the intake, not at the rear. It's hard to miss, it's got a square plug just like the rest of the injectors, and a hard tube going into the top of the injector to supply fuel from the fuel rail. Chances are very good that the CSI is not the problem.
When you checked the codes did you at least get code 12 three times? If you didn't get code 12, you're doing it wrong, or the ECM is shot. Code 12 tells you that you're in service mode, and that the computer is responding as it should.
Fix the obvious problem (the code) first, and deal with the rest later. Following a code is easy. Trying to diagnose a half dozen symptoms as one issue is a bit of a chore.
Yes I get the 12 code. The last time I got it to come on by going down the highway with AC for while. I tried the code again and I think it read a code but I missed it the first time. t then only read 12 over and over. Its strange to me only comes on when running over 60 mph with AC on for a while. I can drive highway without AC or around town with AC and light never comes on. What is the stock thermostat supposed to be? Temp seems low to me. Runs 160 down the highway. I am going to check the fuel pressure today. If the fuel pump isnt coming on when key on but runs when started what would cause this?
Potentially a bad fuel pump relay. At least on the later EFI cars, the fuel pump relay powers the pump briefly (couple seconds) when the key is first turned to on. If the relay fails, a redundancy is built in to power the fuel pump when the oil pressure switch senses pressure. The symptom is cold starts crank until oil pressure comes up, then the engine starts. Warm starts are unaffected because the fuel system maintains pressure after the engine is turned off.
Potentially a bad fuel pump relay. At least on the later EFI cars, the fuel pump relay powers the pump briefly (couple seconds) when the key is first turned to on. If the relay fails, a redundancy is built in to power the fuel pump when the oil pressure switch senses pressure. The symptom is cold starts crank until oil pressure comes up, then the engine starts. Warm starts are unaffected because the fuel system maintains pressure after the engine is turned off.
Here is what I found today. I hooked up fuel pressure tester. Turned on switch and pressure went up to 42 psi for a few seconds then dropped back to zero. Heard the pump go that time. I started engine and it took a few seconds to start. Not real long but not right off. While idling the pressure was around 37-38 psi. When revving engine the pressure jumped up a few psi to 40-42 psi. The starting issue is not same every time. It does start right up if it was just running but if cold or hot after sitting for a 10-15 minutes the starting is a bit longer and sometimes requires a bit of throttle to get it to go. Thoughts? I checked resistance of my injectors cold and hot and all read between 16.8-17.2 both cold or hot so coils are good.
Last edited by Dragster Racer; Jul 5, 2019 at 03:47 PM.
From what I read, if the fuel pressure drops quickly after turning off the ignition, it is either a FPR, leaky injector or bad check valve in fuel pump. I pulled vacuum line going into FPR and not gas or smell there. If it was a leaky injector would pressure drop this fast? It went from 42 to 0 in a couple seconds.
I traced the two fuel lines and attached a photo for confirmation. The top fuel line in the photo comes from the FPR and the bottom line goes into the front of the rail on passenger side. The bottom line is the feed, correct? When I pressurized the system and pinched off the feed the pressure dropped fast as before so I ruled out a fuel pump check valve failure. When I pressurized the system and blocked off the return line(bottom in photo that comes from FPR) the system pressure held. I assume this means the FPR is bad? I am not sure I understand this. I pulled the vacuum line on top of the FPR and its dry and no fuel smell. When engine is off is FPR supposed to stop fuel from returning to the tank? Could the diaphragm in the FPR be good so no smell but not sealing the return?
Finally figured this out. I didnt realize the 12 code went three times before it shows you the code. Its a code 32. Says EGR circuit Does this mean EGR valve needs pulled and cleaned?
My engine temp seems to run cool down the highway. It reads 160. Also this code only throws when I have the AC on above 60 mph. Does that all correlate to the temp sensor being the problem?
I believe the wire might be alittle on the short side but it should physically fit in the egr.
If the EGR temperature switch is stuck closed the EGR valve would be open all the time because its sending a signal to open vacuum line to open the EGR valve? If the EGR Temp switch is stuck open it would never activate and open the EGR valve?
Replaced FPR and it didnt fix the problem of not holding fuel pressure in the rail when you turn off the engine. I am not sure what to think now. When I tested the system before changing FPR I could get the pressure to hold when I blocked the return line. Pressure dropped fast without return line blocked so I assumed FPR was bad. I changed FPR and now it wont hold pressure if I block return or feed line. Pressure did seem to drop a bit slower and a couple times the pressure went down to about 15 psi and held before slowly dropping to zero. Could a leaky injector have been holding when I tested the first time and now its leaking? I dont want to keep changing things that arent going to fix it. Resistance on the injector coils were all good. If i pressurize the system and block both the feed and return lines and it still drops it can only be an injector leaking?
Pressurize the fuel system several times by cycling the key to get pump prime.
Then pull the plugs looking for wet plugs is the only on car way to find a leaking injector.
Pressurize the fuel system several times by cycling the key to get pump prime.
Then pull the plugs looking for wet plugs is the only on car way to find a leaking injector.
I was going to try this test but I dont see anyway to access the spark plugs from the top. Too much crap in the way. Are the plugs best accessed from the bottom with car on a lift?
Iirc it’s just iat 6 & 8 that need to be accessed from the bottom.
Whoever at GM engineered that mess should get hit with a whip 50 times. Changing plugs was a nightmare. Anyway I pressurized the fuel line 5 times before changing plugs and didnt find any wet ones. It took me a while to get to all of them so not sure if they would dry out that fast? If its not the regulator and not a leaky injector what could be causing the pressure loss. Since I changed the FPR the leak down is somewhat slower, Used to drop like a rock not it take 3-5 seconds to go to zero. When I was changing the plugs I found a small black hose says ACY-6 in the side of it. Was just laying there when I was doing 6 and 8 plugs. It ran fine, any idea what it goes to? I couldnt see anything missing a hose that I could see.
You have to turn over the engine (with distributor unplugged) to ensure that all cylinders have a chance to get fuel past the intake valve in case it is closed.
Been following along here and one thing I found that fixed my inconsistent hot/cold starts was switching to non ethanol fuel. By my second tank I have not had that issue since.
Do you guys see an issue in the car running @ 160? These TPI cars was designed to run hot like 190 or more, on my 91 I believe the primary fan does not come on until 195. If his temp gauge is accurate could it be that with the load of the AC, The VSS sensing freeway speeds and the ECM seeing a cold reading it is compensating, for this and trowing the code? Just a thought.
If the operating temperature is 160f the engine will not be able to go in closed loop.
Are you referring to the cts throwing a code ?
There is a code 14 and 15 for the cts. These are extreme conditions for the cts extremely high or low.
What bin is it? Some i have seen closed loop temp enable as low as 104-130 deg. 160 would be fine if you had closed loop set for less than 160. Not sure what other settings there are. Have to look. I like running as cool as possible
