I had an engine rebuild done and just picked up the car. The car feels like it lost 100 HP. I mean it feels slow.

Info:

305 rebuild bottom end
stock heads 081 casting
stock cam

I am suspecting a firing order is not proper..
Could someome tell me a firing order for 89 305 TPI? From which side do you count the cyliders?

Also i noticed on pass side that 4 injectors might be connected wrong. The way the wires are sitting just doesn't look right.. Could some take a pic of their injector wire hook up on pass side or is there a way of checking if they are connected right??

The swap was done at the GM dealership so i am assuming that the cam was installed properly..

I need help before the winter..

 

Distributor rotation is clockwise. firing order is 18436572. #1 cly is dr side front. #3 is behind it#5 is behind #3 # 7 is last cyl on dr bank. #2 is pass front #4 is next #6 then last is #8. #1 cly on cap is usually in the 5 o clock position when viewed from top. 12 oclock would be nearest to firewall and 6 o clock is nearest to radiator. Hope this helps.

 

Thank you..

 

I almost forgot to add that the injectors are batch fired. This means that the ecm has 2 drivers. 1 driver fires the drivers side of the engine. The other driver fires the pass side of engine. If the injectors are mixed up, but remain on the same side of engine, all will be well. The length of the wire harness prevents plugging in on wrong SIDE of engine. Also, I have seen some exceptional techs at dealerships. Alot are not qualified to do quality performance work. Some of the new younger techs were in diapers when our cars were born. They don't always have alot of"hands on" with these "old" cars. Check the firing order and let us know the results. If it doesn't solve the problem we can help you find it. Pete

 

Just checked the firing order and it seems correct. Are you sure that TPI have the same firng order?


This is the pic with the injector harness..Looks backward to me. But maybe like you said it doesn't matter.

 

I am sure that the firing order is the same. The wiring (injector) is fine. I would move it for cosmetics. It will function fine though. I would start to chect the other stuff. Check base timing and advance. Also do a vacuum leak check. On a mass air car a vacuum leak will add "false air" to the engine.

 

As Floor guy mentioned, the firing order for your engine is 1-8-4-3-6-5-7-2 regardless of whether it is a 5.0L TBI or a 5.7L TPI.

 

Thanks guys.

I don't have a timing light but i have a scanner. I don't know if that will help me much but i will give it a try.

Tomorro i will go back to the dealer and tell them to doublecheck the timing again..

If timing is ok what other things could be wrong?

 

Vacuum leak, vacuum leak, vacuum leak... As mentioned MAF systems are intolerant of vacuum leaks. Check all of the vacuum hoses, evap cannister, EGR, brake booster, cruise control..etc.

 

They are all good.. I have triple checked.

I was talking to cooworker and he said that it is normal for a new engine to run worse/slower for a while because everything is tight and the friction is making it run like that. He said to break the engine in slowely and it will get better.

I still have to check the ignition timing so when i do get a chance i will update at what it was set at..

 

umm no thats not how it works....it should have the same power now it will have in a year unless you mod it ...

 

INCORRECT. The term batch fire means all injectors fire at the SAME time. Yes, there are two injector drivers inside the ECU but they are connected together internally and have one ONE output. You cannot mix up the connectors.

 

Wait a second, in my holley book it says that batch fire on TPI motors is the same as bank/bank, as in right side then left side fires. not all at once...

In fact even accel DFI book says you cant meter fuel into an open intake valve, which would mean that batch fire is right side then left side.

 

Nope, batch fire on '86-92 3rd gens fire all injectors at the same time. Here's a link to a '86 wire diagram clearly showing the left and right bank are tied together inside the ecu to a single point.

http://www.lt1intake.com/images/22-7.jpg

 

TPI fires bank to bank, not all at once. Your link did not show the diagram you were looking at, I suspect that it is wrong. If you look at this diagram, you will see that the banks are fired individually.Diagram

 

Go here. It has a pic of which wires go where on the distributor.

https://www.thirdgen.org/techbb2/sho...t=firing+order

It worked for me!

 

Well, regardless of your opinion on the firing method of the injectors, its not going to make a damn bit of difference how they are hooked up as long as they're getting juiced properly.

 

I fixed my link, dang tripod server won't let you post links direct. I uploaded it to my server and posted it again. Here's the link again but the one above is fixed.

http://www.lt1intake.com/images/22-7.jpg

My image is direct from GM service manual, unlike your link. I don't know where you got that info but it's incomplete. If you want I'll post the internal wiring diagram of the ecu and you can see again batch fire pulses all 8 injectors at the same time.

 

I wish I could argue that, but John wins. I apologize for posting incorrect information.

 

He gave a really good reason in another thread on the DIY-PROM board.

 

Then whats all this crap in the Haltec / Accel / Holley manual about not metering fuel into an open intake valve or it will cause drivability problems? obviouselly some fuel will enter an open intake valve if they all fire at once. where is that logic?

 

Dunno, sales pitch?

 

I found that one of the plug wires was separated from the boot and the other wire was burned right to the core.

Also i found that a Gm mechanic left one runner to base bolt loose and the rest of the bolts on plenum/runners were not that tight..

The car runs awesome now. I am still taking it easy on the engine as i only put on 60 miles or so..

Thanks for everyones help..