Hey, I posted this in the van section a few days ago but its hard to get a reply out there sometimes. Ive seen several people on here with the same issue as me but it doesnt seem to get sorted out. My 87 ford ranger has the same issue so I think its gotta be pretty common with these older fords. My 1989 e150 with the 302 has almost always had an issue with the idle surging and dropping when starting the engine for the first time of the day. I learned to just live with it as it only happens for 15 or so seconds when I first start the van. Sometimes the engine dies and I have to start it again but lately its been wanting to die a lot more often so I've learned to just baby it with a little gas when the idle drops too low and after 15 or so seconds it's able to keep itself alive without the gas and I go on with my day. Well today I decided to do a few things to the van and I also wanted to see if it would start and stay running on its own without me babying it with the gas and it wouldn't. I tried Over and over but it would just die right after I started it. This is a bit disconcerting. I hooked up my fuel gauge to the rail and fuel pressure looks good (high 30's). I have a lot of random spare parts from other ford vans for trouble shooting so one at a time I swapped the IAC valve/solenoid, MAP sensor, ECU and nothing really made a difference. I checked the cap and rotor, checked my vacuum canisters to make sure they hold vacuum, looked at all the vacuum lines trying to find anything out of the ordinary that might be leaking but Ive yet to find anything. In the past I've cleaned the injectors, replaced the intake manifold gasket, throttle body gasket, throttle position sensor, coolant temp sensor, air charge temp sensor, among many other things. I have yet to adjust or check the timing on this van, is that something I should look into given the symptoms? I have a timing light but haven't taken the time to look into how to adjust the timing on this van. I'm convinced its something vacuum related, maybe EVAP related? I need to learn more about the TAB and TAD solenoids, diverter valve, smog pump etc.. I read the TAD solenoid is active before the engine warms up, I'm wondering if a bad TAD valve could cause the symptoms I have and if 15 or seconds of the engine running is all it would take for the TAD to turn off in normal operation? There is no vacuum coming from the TAD solenoid to the air diverter valve while the engine is running, Is that normal? Any help would be greatly appreciated as I've basically fixed every issue with the van since I purchased it except this one annoying one!

 

Here's a video of what the sporadic idle sounds like on a cold start and if you watch til the end you will hear it finally correct itself to the proper idle speed and then its good the rest of the day until I let it sit over night or so and its back to the same thing next cold start. If you listen it sounds like it evens out suddenly like a switch has been flipped. Its not a gradual change. Link to the video:


https://imgur.com/0bbIeDM

 

Did you ever find a solution to your issue? I have a 89 E150 club wagon with the 302 V8 and it has the exact same issue. Like you, I put up with it last year but was hoping to fix it this spring once it warms up. I'd appreciate any feedback.

Thanks!

 

Not really. My other thread on this issue went on for a while as I tested different sensors and chased a few vacuum leaks. I did end up having a few cracked vacuum lines and I replaced them all with silicone tubing. My air charge temp sensor was also a dud. I had a bad check valve in my secondary air/smog system. I fixed all these things as well as did a tune up since it was about due for one and it doesn't die on a cold start as often as it was when I started this thread but it still often has the sporadic idle issue on cold start. I just give it a tiny bit of gas when the idle first drops and then it hangs in there from then on. My '87 ranger does the same thing. Old fords maybe.