Lately my 88GT wants to stall on initial start-up. She bogs done to almost nothing then starts to smooth out and eventually idles and runs fine. It's getting progressively worse and will probably start stalling out on me next. I've thoroughly cleaned the throttle body with seafoam while keeping the engine going and it seemed to help, but just comes back. I can hear the fuel pump turn on when I turn the key so the relay is fine. I don't suspect the following because I replaced them a few months back: MAT sensor in the air cleaner, replaced the fuel filter, complete tune-up with new plugs, wires, coils and air filter. Because the it's been getting worse I don't suspect a vaccum leak nor a bad ground. Time to replace the IAC or MAP sensor? Maybe the cold start injector switch? Thanks for some help

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guess what..mine was doing the exact same thing..its like in the morning i got used to giving it a little gas at start up to avoid the "stall"...well since then i changed the cpu..and oh yeah..entire engine!! and it still does it!!...im thinking its the cold start injector..has to be..its the only thing left on mine that was original....just has to be..

quote Originally posted by 88 Silver Formula: guess what..mine was doing the exact same thing..its like in the morning i got used to giving it a little gas at start up to avoid the "stall"...well since then i changed the cpu..and oh yeah..entire engine!! and it still does it!!...im thinking its the cold start injector..has to be..its the only thing left on mine that was original....just has to be..

Thanks for sharing your experience. Maybe I should start with the cold start injector switch. Is the cold start injector itself a different component? I don't see it here http://www.secureleadercom....earchfield=inetsdesc

Wow, this ended up on page 2 real quick. Can anyone else chime in that has this experience in their V6? I guess other suspects that I haven't replaced yet are the O2 sensor, IAC valve and EGR valve. I'd hate to start replacing parts though that are not bad yet.
Marc

quote Originally posted by 88 Silver Formula: im thinking its the cold start injector..has to be..its the only thing left on mine that was original....just has to be..

The switch didn't solve my problem. I picked one up in this lot at e-bay last week http://cgi.ebay.com/ebaymot...m=&item=110130300540 and swapped it out today but the problem still persists. I give up trying to get an answer here. The days of getting five or six replies in a day to a tech question like this are gone! Where's theogre when you need him

The only way a CSI would cause your problem is if it was leaking. A fuel pressure leak down test would indicate where there are inj. leaking or not.
The CSI is only powered while the starter is engaged since it gets it's power from the starter circuit. That is why changing the CSI switch did nothing.

Do you think it is running rich or lean? Usually issues at startup are related to fuel pressure, CTS, injectors, TPS, and MAP.

I would check your fuel pressure even though you changed the pump to eliminate that.
Next I would check the CTS via Winaldl or with an ohm meter.

quote Originally posted by Dodgerunner: The only way a CSI would cause your problem is if it was leaking. A fuel pressure leak down test would indicate where there are inj. leaking or not. The CSI is only powered while the starter is engaged since it gets it's power from the starter circuit. That is why changing the CSI switch did nothing. Do you think it is running rich or lean? Usually issues at startup are related to fuel pressure, CTS, injectors, TPS, and MAP. I would check your fuel pressure even though you changed the pump to eliminate that. Next I would check the CTS via Winaldl or with an ohm meter.

I don't think I'm running rich or lean. Idles and runs nicely after it chugs down to almost stalling at initial start-up. I'll have my pressure checked but I doubt I have anything leaking. My previous GT had a leaky injector and I could smell the fuel before start-up! I can't smell any fuel with my latest GT.
I have a few used spare TPS's and MAP's so I'll swap them and see if it makes a difference. What is the CTS? Also I replaced the CSI switch, is the cold start injector a separate part than the injectors themselves?
Also....THANK-YOU for taking the time to help me get this fixed before it becomes a bigger prob
Marc

[This message has been edited by Gokart (edited 06-03-2007).]

quote Originally posted by Gokart: What is the CTS? Also I replaced the CSI switch, is the cold start injector a separate part than the injectors themselves? Also....

Marc, the CTS is the coolant sensor. It plays a big part in determining fuel mixture. If it is going bad and the resistance is staying low it will make the engine lean at startup since it thinks the engine is warmer than it is. In case you don't know it's located below the thermostat housing the sticks out horz. right above the water pump.

As far a the CSI it works like this.....The power comes from the starter, thru the cold start switch and to the cold start injector which is located behind the distributor. It sticks into the end of the lower manifold and is separate from the other 6.
The cold start switch only supplies power to the CSI when it is below about 40*F so in warmer weather it should never close. When it does there is only power to the CSI while cranking the engine. I'd have to look, but I think the switch even cuts off the power after 2sec. if you continue to crank, but not sure on that.

[This message has been edited by Dodgerunner (edited 06-03-2007).]

ive unpluged my cold start injector via electric and still has same problem....mabey it is leaking..leaking overnight and maki8ng a "puddle" in the intake cause mine only does it when its been sitting at least overnight.

quote Originally posted by Dodgerunner: Marc, the CTS is the coolant sensor. It plays a big part in determining fuel mixture. If it is going bad and the resistance is staying low it will make the engine lean at startup since it thinks the engine is warmer than it is. In case you don't know it's located below the thermostat housing the sticks out horz. right above the water pump

Thanks. I have a couple of spares so I'll swap it out and see what happens.

quote Originally posted by Dodgerunner: As far a the CSI it works like this.....The power comes from the starter, thru the cold start switch and to the cold start injector which is located behind the distributor. It sticks into the end of the lower manifold and is separate from the other 6. The cold start switch only supplies power to the CSI when it is below about 40*F so in warmer weather it should never close. When it does there is only power to the CSI while cranking the engine. I'd have to look, but I think the switch even cuts off the power after 2sec. if you continue to crank, but not sure on that.

I guess it can't be the CSI then. It's been like summer here already on the Cape with temps in the 70's.

quote Originally posted by 88 Silver Formula: ive unpluged my cold start injector via electric and still has same problem....mabey it is leaking..leaking overnight and maki8ng a "puddle" in the intake cause mine only does it when its been sitting at least overnight.

My previous 88GT had this problem. I could actually smell the fuel when sniffing around the intake. Shouldn't you smell fuel if this was the problem?

[This message has been edited by Gokart (edited 06-04-2007).]

My V6 had that problem once. It was the IAT sensor (sometimes known as the Incoming Air Charge sensor) in the air filter housing.

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1986 SE 350 V8

My diagnosis is that the engine is too small.

quote Originally posted by tesmith66: My V6 had that problem once. It was the IAT sensor (sometimes known as the Incoming Air Charge sensor) in the air filter housing.

Replaced it already months ago.

quote Originally posted by Gokart: I don't suspect the following because I replaced them a few months back: MAT sensor in the air cleaner

Maybe it's crapping out already or I need to tighten it more so it's closer to the air cleaner?

quote Originally posted by CTFieroGT87: My diagnosis is that the engine is too small.

I think you hit the nail on the head and you need to help me fix that problem! Just bring that 350 of yours over here again

my bet would be the CTS, like dodgerunner said, your temperature sensors are the primary sensors the computer uses until it slips into closed loop and uses the O2 to adjust fuel trim. I would check you CTS next, let us know how it goes.

Have you checked the IAC for build up ? Does the car run better once warmed up ?
I was working on my cold start problem, and the only thing I found was some carbon build-up on the IAC valve.

quote Originally posted by Jrgicehc: my bet would be the CTS, like dodgerunner said, your temperature sensors are the primary sensors the computer uses until it slips into closed loop and uses the O2 to adjust fuel trim. I would check you CTS next, let us know how it goes.

I have a spare but can't see where it goes! Anyone have a pic or describe where it's located.

quote Originally posted by StockGT: Have you checked the IAC for build up ? Does the car run better once warmed up ? I was working on my cold start problem, and the only thing I found was some carbon build-up on the IAC valve.

I'd like to remove it and clean it too but I don't have a metric wrench to fit it and my adjustable wrench doesn't open far enough to get around it! Anyone know what size it is?
Thanks for the help!
Marc

Hope this helps. Winaldl and a cable makes it easier to check.

[This message has been edited by Dodgerunner (edited 06-05-2007).]

quote Originally posted by Dodgerunner: Hope this helps. Winaldl and a cable makes it easier to check.

Thank-you! You have been a huge help!

Anyone else know what size wrench I need to get around the IAC valve?

I have another idea for you. Check your Throttle body idle adjust screw, which is actually just the throttle body butterfly adjustment. If you can see the screw, meaning someone removed the brass cap that protects it, the it might have worked it's way loose. This happened to me and the car became nearly undriveable. What happens is the butterfly becomes nearly closed and the engine can only get air through the IAC and the engine wants to die. If the screw is too tight you get exactly the opposite problem with the butterfly being too wide at idle and you always have too much air which forces the engine to add more fuel and you end up with a high idle, and still you will bog down from a lean mixture on WOT.

Ok Gokart, it goes without saying but I'll say it anyways for the benefit of our younger members.

Double check your ground strap, negative (-) battery to block and chassis cables, then check your main output wire from your alternator up to your main wiring harness then up to your positive (+) battery post. Hows your battery acid levels? Have your electrical system load tested, let's make sure your electrical is up to snuff. Bad electrical connections = inconsistant power = inconsistant sensor readings back to your ECM = inconsistant idle. You could even try to swap in a known good battery to see if the symptoms can be duplicated?

Make sure that your sensor connections are absolutely free of any corrosion, slather some dielectric grease afterwards. You didn't mention replacing your gas filter, you may want to go ahead and try that also, you could have got a poor batch of gas, clogging it somewhat. double check your air filter again.

My thoughts are to make certain the electrical system is absolutely perfect, replacing sensors won't do a bit of good if the electrcal system is crummy. I'm thinking electrical because the load on the battery is the greatest at first start up, what do you think?

I used a 32 mm socket to remove the IAC.

Tagging onto Jetman's post here is some information on checking grounds etc.

https://www.fiero.nl/forum/Forum2/HTML/082148.html

quote Originally posted by Dodgerunner: Hope this helps. Winaldl and a cable makes it easier to check.

I swapped it out tonight and it actually seemed to start better already! Fairly easy to get to after removing the 10mm screw holding on the EGR solenoid. I removed the sensor with a 3/4 deep socket. I had a new one from a different lot of parts I picked up at e-bay. The real test will be tomorrow. It always wants to stall right when I start her from work to come home in the afternoon. I'll post the results here tomorrow.

quote Originally posted by connecticutFIERO: I have another idea for you. Check your Throttle body idle adjust screw, which is actually just the throttle body butterfly adjustment. If you can see the screw, meaning someone removed the brass cap that protects it, the it might have worked it's way loose. This happened to me and the car became nearly undriveable. What happens is the butterfly becomes nearly closed and the engine can only get air through the IAC and the engine wants to die. If the screw is too tight you get exactly the opposite problem with the butterfly being too wide at idle and you always have too much air which forces the engine to add more fuel and you end up with a high idle, and still you will bog down from a lean mixture on WOT.

As far as I can tell it hasn't been tampered with but great info. Thanks for posting!

quote Originally posted by jetman: Ok Gokart, it goes without saying but I'll say it anyways for the benefit of our younger members. Double check your ground strap, negative (-) battery to block and chassis cables, then check your main output wire from your alternator up to your main wiring harness then up to your positive (+) battery post. Hows your battery acid levels? Have your electrical system load tested, let's make sure your electrical is up to snuff. Bad electrical connections = inconsistant power = inconsistant sensor readings back to your ECM = inconsistant idle. You could even try to swap in a known good battery to see if the symptoms can be duplicated? Make sure that your sensor connections are absolutely free of any corrosion, slather some dielectric grease afterwards. You didn't mention replacing your gas filter, you may want to go ahead and try that also, you could have got a poor batch of gas, clogging it somewhat. double check your air filter again. My thoughts are to make certain the electrical system is absolutely perfect, replacing sensors won't do a bit of good if the electrcal system is crummy. I'm thinking electrical because the load on the battery is the greatest at first start up, what do you think?

Good advice Stooge! I did replace my fuel filter about six months ago but my grounds may need some attention. This will happen when I'm on vacation for two weeks next month and I have to replace my battery tray and bracket anyhoo. I'll have my battery checked too if the problem persists after tomorrow. I made sure to use dielectric grease on my CTS and CSI plugs too. I noticed you were having similar problems when I was doing a search last week. https://www.fiero.nl/forum/A...070315-2-076697.html Does yours still persist?

quote Originally posted by StockGT: I used a 32 mm socket to remove the IAC.

Thanks Stock! I have alot of tools but no wrenches over 18mm. I'll have to pick one up tomorrow. I'd like to clean the IAC regardless of results.

quote Originally posted by Dodgerunner: Tagging onto Jetman's post here is some information on checking grounds etc. https://www.fiero.nl/forum/Forum2/HTML/082148.html

Great write-up! Should've got more replies. Added to my faves.

[This message has been edited by Gokart (edited 06-06-2007).]

marc with grounding problems, i dont believe it, you should see the setup he put on my car.