New to me 87

[Jims86]

Prom is the original 305. Injectors are also from the 305. So I am heading out tomm looking for Injectors and a prom. Do you think I should pick up a ESC and knock sensor from the parts house? I know it doesn't matter, but I do have a new TPS and O2 sensor. The TPS is suspect to be bad and the O2 is almost broke in half.

if its not a burdon on your wallet, it cant hurt to pick up everything for a 350.

 

[JamesDEvans007]

New prom, O2, TPS, knock sensor, cleaned/rebuilt Tbi and installed correct Injectors, truck runs better. However it idles up and down until it warms up. Then it high idles around 12-1300. Sometimes it will drop down where its supposed to be. Doesn't start as quick as I think it should, but sometimes it fires right up when its warm only. Hit or miss. Any ideas?

 

[Jims86]

New prom, O2, TPS, knock sensor, cleaned/rebuilt Tbi and installed correct Injectors, truck runs better. However it idles up and down until it warms up. Then it high idles around 12-1300. Sometimes it will drop down where its supposed to be. Doesn't start as quick as I think it should, but sometimes it fires right up when its warm only. Hit or miss. Any ideas?

Make sure your timing is at 0*.
Disconnect the battery for 15 seconds, then re connect and go for a 30 minute drive, and see if it throws any check engine light.
get a fuel pressure tester for TBI, it has a specific adaptor to go in the fuel line.
not sure what tools you have at your disposal, but the before mentioned, as well as a tachometer, and a digital volt meter will be very handy in setting idle, and throttle position sensor.
You will want to get a can of Carb cleaner to check for any vacuum leaks... which is what usually causes surging. If you dont have a tach right now, a good way to set the throttle blades is to look inside the barrels, there is a vacuum port hole at the front surface of each. you want to turn the idle stop screw until the top surface of the blades are right at the bottom of those ports. you idle screw may be capped. its easily removed with a punch, and then dig it out. the driver size is t-20.

 

[JamesDEvans007]

Make sure your timing is at 0*.
Disconnect the battery for 15 seconds, then re connect and go for a 30 minute drive, and see if it throws any check engine light.
get a fuel pressure tester for TBI, it has a specific adaptor to go in the fuel line.
not sure what tools you have at your disposal, but the before mentioned, as well as a tachometer, and a digital volt meter will be very handy in setting idle, and throttle position sensor.
You will want to get a can of Carb cleaner to check for any vacuum leaks... which is what usually causes surging. If you dont have a tach right now, a good way to set the throttle blades is to look inside the barrels, there is a vacuum port hole at the front surface of each. you want to turn the idle stop screw until the top surface of the blades are right at the bottom of those ports. you idle screw may be capped. its easily removed with a punch, and then dig it out. the driver size is t-20.

Yeah upon further research I see the tps isn't a bolt on part. Has to be set when installed. Didn't know that, that's prob my high idle issue. I had the page out when I cleaned the Tbi, but also didn't know the pintle was adjustable. I can't find the setting length for the pintle to the base. Found plenty of relearn info, but not the length setting.

 

[Jims86]

Yeah upon further research I see the tps isn't a bolt on part. Has to be set when installed. Didn't know that, that's prob my high idle issue. I had the page out when I cleaned the Tbi, but also didn't know the pintle was adjustable. I can't find the setting length for the pintle to the base. Found plenty of relearn info, but not the length setting.

Nahh, just bolt it on, and do that adjustment i was talking about.
do you know how to pull trouble codes?

 

[JamesDEvans007]

Nahh, just bolt it on, and do that adjustment i was talking about.
do you know how to pull trouble codes?

Yeah, jump A and B terminals. I thought the pintle had to be adjusted to a certain length.

 

[Jims86]

Ok, so to reset the idle without a tach,( Engine warmed up)after you adjust the throttle blades like mentioned before, ground a and b, turn the key on, and wait 30 seconds.
Turn the key off, take the juper out of A and B, and disconnect the battery for 15 seconds.
Reconnect the battery, start up, and go for a drive so the ECM can re learn everything.
If it still surges, you might have a vacuum leak. it should idle in drive between 550 and 650, depending on what is programmed into the prom chip.

 

[JamesDEvans007]

Ok, so to reset the idle without a tach,( Engine warmed up)after you adjust the throttle blades like mentioned before, ground a and b, turn the key on, and wait 30 seconds.
Turn the key off, take the juper out of A and B, and disconnect the battery for 15 seconds.
Reconnect the battery, start up, and go for a drive so the ECM can re learn everything.
If it still surges, you might have a vacuum leak. it should idle in drive between 550 and 650, depending on what is programmed into the prom chip.

I found that the pintle is supposed to be no more than 1 1/8 inch from base to tip. I also forgot to put the dang gasket on the IAC when I reinstalled it, well let me correct that, there wasn't one there when I took it out. And I had no clue where that last gasket went. Wonder if that could be the cause for the surge...could it suck enough air there to cause the surge? It was surging prior to the prom and Injector change till it was warmed up...even with the cts unhooked. Same as its doing now.

My repair manual has the base idle relearn procedure in it. Engine at normal operating temp...It says KOEO (key on engine off) jump a and b for 30 seconds, disconnect the plug from IAC, unjump a and b, and start the truck. Adjust idle between 500-600 rpm in drive. Shut off the truck and reconnect the plug to the IAC. Adjust the TPS to 0.045-0.060. Recheck the TPS adjustment after tightening, start and verify proper operation. Just a hair diffrent from what you said. It also said to do this only if parts were replaced in the TBI...which I did fully clean, rebuild, and replace the Injectors.

I have a aftermarket tach in it, how good of accuracy it has, that's the question. I guess just set it around 550ish according to it.

I really appreciate all your help and insight...past and future...its helped tremendously, I must say I joined the right forum!

 

[Jims86]

I found that the pintle is supposed to be no more than 1 1/8 inch from base to tip. I also forgot to put the dang gasket on the IAC when I reinstalled it, well let me correct that, there wasn't one there when I took it out. And I had no clue where that last gasket went. Wonder if that could be the cause for the surge...could it suck enough air there to cause the surge? It was surging prior to the prom and Injector change till it was warmed up...even with the cts unhooked. Same as its doing now.

My repair manual has the base idle relearn procedure in it. Engine at normal operating temp...It says KOEO (key on engine off) jump a and b for 30 seconds, disconnect the plug from IAC, unjump a and b, and start the truck. Adjust idle between 500-600 rpm in drive. Shut off the truck and reconnect the plug to the IAC. Adjust the TPS to 0.045-0.060. Recheck the TPS adjustment after tightening, start and verify proper operation. Just a hair diffrent from what you said. It also said to do this only if parts were replaced in the TBI...which I did fully clean, rebuild, and replace the Injectors.

I have a aftermarket tach in it, how good of accuracy it has, that's the question. I guess just set it around 550ish according to it.

I really appreciate all your help and insight...past and future...its helped tremendously, I must say I joined the right forum!

Yeah, didnt know you had a tach. I usually go for the lowest possible. A lot of the TBI setups are supposed to idle around 625, so with the IAC closed, I shoot for 100 less. GM manual says set it to 500. as far as Im concerned, the lowest you can get, and still have a good charge from the alternator...its all good.

 

[Jims86]

As far as surges, running rich and low idle...i have been uncovering some wierd ****...stay tuned.

 

[JamesDEvans007]

Looks like tomm I am heading out to try and finish up with the ole truck. Trans filter and fluid change, belts, new locks in the doors, wipers, and some other odd and end stuff. If I get it running good and have time and daylight left, a remote start w/keyless is going in it. Then all I will have left is what to do about the seat. Man I wish I could just bolt in some late 90s model Caddy Deville seats in her...plush, heated, and comfortable!

 

[JamesDEvans007]

I got the ole square all buttoned up. Everything is done except for the seat and keyless/remote start. Even installed an auto dim/compass mirror thanks to the write up on this site. Gonna drive it the next few days to make sure it is all good to go.

I am still having a high idle issue. In park I am seeing 900-1100ish. No surging, just always somewhere between there. She runs smooth and will hold her own quite nicely at 80 on the interstate. I did the relearn, adjusted the tps to 0.45. The only thing I didn't do was disconnect the battery before firing it back up and driving it. And when I went for a drive, for about 40 minutes, I wasn't in stop and go, all back country roads. Could this be the reason? Should I do it all over again? Any thoughts?